Nitrogen containing heterocyclic compounds

ABSTRACT

Compounds of Formula (I), their preparation and use in preventing or treating bacterial infections are disclosed.

RELATED PATENT APPLICATIONS

This patent application is a continuation of Ser. No. 14/113,980, filedNov. 30, 2013, which claims the benefit of Indian Provisional PatentApplication No. 2424/MUM/2011 filed on Aug. 30, 2011, the disclosures ofwhich are incorporated herein by reference in its entirety as if fullyrewritten herein. All references including patents, patent applications,and literature cited in the specification are expressly incorporatedherein by reference in their entirety.

FIELD OF THE INVENTION

The invention relates to nitrogen containing heterocyclic compounds,their preparation and their use in preventing and/or treating bacterialinfections.

BACKGROUND OF THE INVENTION

Emergence of bacterial resistance to known antibacterial agents isbecoming a major challenge in treating bacterial infections. One wayforward to treat bacterial infections, and especially those caused byresistant bacteria, is to develop newer antibacterial agents that canovercome the bacterial resistance. Coates et al. (Br. J. Pharmacol.2007; 152(8), 1147-1154.) have reviewed novel approaches to developingnew antibiotics. However, the development of new antibacterial agents isa challenging task. For example, Gwynn et al. (Annals of the New YorkAcademy of Sciences, 2010, 1213: 5-19) have reviewed the challenges inthe discovery of antibacterial agents.

Several antibacterial agents have been described in the prior art (forexample, see PCT International Application Nos. PCT/US2010/060923,PCT/EP2010/067647, PCT/US2010/052109, PCT/US2010/048109,PCT/GB2009/050609, PCT/EP2009/056178 and PCT/US2009/041200). However,there remains a need for potent antibacterial agents for preventingand/or treating bacterial infections, including those caused by bacteriathat are resistant to known antibacterial agents.

The inventors have surprisingly discovered nitrogen containingheterocyclic compounds with antibacterial properties.

SUMMARY OF THE INVENTION

Accordingly there are provided nitrogen containing heterocycliccompounds, methods for preparation of these compounds, pharmaceuticalcompositions comprising these compounds, and method for preventing ortreating bacterial infection in a subject using these compounds.

In one general aspect, there are provided compounds of Formula (I):

or a stereoisomer or a pharmaceutically acceptable salt thereof;wherein:

Q is heteroaryl;

R₁ is:

-   -   (a) hydrogen,    -   (b) (CO)_(n)—R₃, or    -   (c) COOR₄,

n is 0, 1 or 2;

R₂ is:

-   -   (a) SO₃M,    -   (b) SO₂NH₂,    -   (c) PO₃M,    -   (d) CH₂COOM,    -   (e) CF₂COOM,    -   (f) CHFCOOM, or    -   (g) CF₃;

M is hydrogen or a cation;

R₃ is:

-   -   (a) hydrogen,    -   (b) C₁-C₆ alkyl optionally substituted with one or more        substituents independently selected from halogen, OR₅, CN,        COOR₅, CONR₆R₇, NR₆R₇, NR₅COR₈, NR₅CONR₆R₇, heterocyclyl,        heteroaryl, cycloalkyl or aryl,    -   (c) CN,    -   (d) NR₆R₇,    -   (e) CONR₆R₇,    -   (f) NHCONR₆R₇,    -   (g) aryl optionally substituted with one or more substituents        independently selected from C₁-C₆ alkyl, OR₅, NR₆R₇, halogen,        CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, or        NHCONR₆R₇,    -   (h) heterocyclyl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₆R₇,    -   (i) heteroaryl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₆R₇,    -   (j) cycloalkyl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₆R₇,    -   (k) cycloalkyl substituted with C₁-C₆ alkyl wherein C₁-C₆ alkyl        is further substituted with one or more substituents        independently selected from OR₅, NR₆R₇, halogen, CN, or CONR₆R₇,        or    -   (l) OR₈;

R₄ is:

-   -   (a) hydrogen,    -   (b) C₁-C₆ alkyl optionally substituted with one or more        substituents independently selected from halogen, OR₅, CN,        COOR₅, CONR₆R₇, NR₆R₇, NR₅COR₈, heterocyclyl, heteroaryl,        cycloalkyl or aryl,    -   (c) aryl optionally substituted with one or more substituents        independently selected from C₁-C₆ alkyl, OR₅, NR₆R₇, halogen,        CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, or        NHCONR₆R₇,    -   (d) heterocyclyl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₆R₇,    -   (e) heteroaryl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₆R₇, or    -   (f) cycloalkyl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₆R₇;

R₅ and R₈ are each independently:

-   -   (a) hydrogen, or    -   (b) C₁-C₆ alkyl optionally substituted with one or more        substituents independently selected from halogen, CN, CONR₆R₇,        NR₆R₇, heterocyclyl, heteroaryl, cycloalkyl or aryl;

R₆ and R₇ are each independently:

-   -   (a) hydrogen,    -   (b) C₁-C₆ alkyl optionally substituted with one or more        substituents independently selected from halogen, OR₅, CN,        COOR₅, CONR₅R₈, NR₅R₈, NR₅COR₈, heterocyclyl, heteroaryl,        cycloalkyl or aryl,    -   (c) aryl optionally substituted with one or more substituents        independently selected from C₁-C₆ alkyl, OR₅, NR₅R₈, halogen,        CN, CONR₅R₈, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, or        NHCONR₅R₈,    -   (d) heterocyclyl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₅R₈, halogen, CN, CONR₅R₈, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₅R₈,    -   (e) heteroaryl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₅R₈, halogen, CN, CONR₅R₈, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₅R₈,    -   (f) cycloalkyl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₅R₈, halogen, CN, CONR₅R₈, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₅R₈, or    -   (g) R₆ and R₇ are joined together to form a four to seven member        ring.

In another general aspect, there are provided pharmaceuticalcompositions comprising a compound of Formula (I), or a stereoisomer ora pharmaceutically acceptable salt thereof.

In another general aspect, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of acompound of Formula (I) or a stereoisomer or a pharmaceuticallyacceptable salt thereof.

In another general aspect, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, wherein themethod comprises administering to said subject a pharmaceuticallyeffective amount of a compound of Formula (I) or a stereoisomer or apharmaceutically acceptable salt thereof.

In another general aspect, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of apharmaceutical composition comprising a compound of Formula (I) or astereoisomer or a pharmaceutically acceptable salt thereof.

In yet another general aspect, there is provided a method for preventingor treating a bacterial infection in a subject, said infection beingcaused by bacteria producing one or more beta-lactamase enzymes, whereinthe method comprises administering to said subject a pharmaceuticallyeffective amount of a pharmaceutical composition comprising a compoundof Formula (I) or a stereoisomer or a pharmaceutically acceptable saltthereof.

In another general aspect, there are provided pharmaceuticalcompositions comprising: (a) a compound of Formula (I), or astereoisomer or a pharmaceutically acceptable salt thereof, and (b) atleast one beta-lactamase inhibitor selected from sulbactam, tazobactam,clavulanic acid, or a pharmaceutically acceptable derivative thereof.

In another general aspect, there are provided pharmaceuticalcompositions comprising: (a) a compound of Formula (I), or astereoisomer or a pharmaceutically acceptable salt thereof, and (b) atleast one antibacterial agent or a pharmaceutically acceptablederivative thereof.

In another general aspect, there are provided pharmaceuticalcompositions comprising: (a) a compound of Formula (I), or astereoisomer or a pharmaceutically acceptable salt thereof, (b) at leastone beta-lactamase inhibitor selected from sulbactam, tazobactam,clavulanic acid, or a pharmaceutically acceptable derivative thereof,and (c) at least one antibacterial agent or a pharmaceuticallyacceptable derivative thereof.

In another general aspect, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of apharmaceutical composition comprising: (a) a compound of Formula (I), ora stereoisomer or a pharmaceutically acceptable salt thereof, and (b) atleast one beta-lactamase inhibitor selected from sulbactam, tazobactam,clavulanic acid, or a pharmaceutically acceptable derivative thereof.

In yet another general aspect, there is provided a method for preventingor treating a bacterial infection in a subject, said infection beingcaused by bacteria producing one or more beta-lactamase enzymes, whereinthe method comprises administering to said subject a pharmaceuticallyeffective amount of a pharmaceutical composition comprising: (a) acompound of Formula (I), or a stereoisomer or a pharmaceuticallyacceptable salt thereof, and (b) at least one beta-lactamase inhibitorselected from sulbactam, tazobactam, clavulanic acid, or apharmaceutically acceptable derivative thereof.

In another general aspect, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of apharmaceutical composition comprising: (a) a compound of Formula (I), ora stereoisomer or a pharmaceutically acceptable salt thereof, and (b) atleast one antibacterial agent or a pharmaceutically acceptablederivative thereof.

In yet another general aspect, there is provided a method for preventingor treating a bacterial infection in a subject, said infection beingcaused by bacteria producing one or more beta-lactamase enzymes, whereinthe method comprises administering to said subject a pharmaceuticallyeffective amount of a pharmaceutical composition comprising: (a) acompound of Formula (I), or a stereoisomer or a pharmaceuticallyacceptable salt thereof, and (b) at least one antibacterial agent or apharmaceutically acceptable derivative thereof.

In another general aspect, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of apharmaceutical composition comprising: (a) a compound of Formula (I), ora stereoisomer or a pharmaceutically acceptable salt thereof, (b) atleast one beta-lactamase inhibitor selected from sulbactam, tazobactam,clavulanic acid, or a pharmaceutically acceptable derivative thereof,and (c) at least one antibacterial agent or a pharmaceuticallyacceptable derivative thereof.

In yet another general aspect, there is provided a method for preventingor treating a bacterial infection in a subject, said infection beingcaused by bacteria producing one or more beta-lactamase enzymes, whereinthe method comprises administering to said subject a pharmaceuticallyeffective amount of a pharmaceutical composition comprising: (a) acompound of Formula (I), or a stereoisomer or a pharmaceuticallyacceptable salt thereof, (b) at least one beta-lactamase inhibitorselected from sulbactam, tazobactam, clavulanic acid, or apharmaceutically acceptable derivative thereof, and (c) at least oneantibacterial agent or a pharmaceutically acceptable derivative thereof.

In another general aspect, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of:(a) a compound of Formula (I), or a stereoisomer or a pharmaceuticallyacceptable salt thereof, and (b) at least one beta-lactamase inhibitorselected from sulbactam, tazobactam, clavulanic acid, or apharmaceutically acceptable derivative thereof.

In yet another general aspect, there is provided a method for preventingor treating a bacterial infection in a subject, said infection beingcaused by bacteria producing one or more beta-lactamase enzymes, whereinthe method comprises administering to said subject a pharmaceuticallyeffective amount of: (a) a compound of Formula (I), or a stereoisomer ora pharmaceutically acceptable salt thereof, and (b) at least onebeta-lactamase inhibitor selected from sulbactam, tazobactam, clavulanicacid, or a pharmaceutically acceptable derivative thereof.

In another general aspect, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of:(a) a compound of Formula (I), or a stereoisomer or a pharmaceuticallyacceptable salt thereof, and (b) at least one antibacterial agent or apharmaceutically acceptable derivative thereof.

In yet another general aspect, there is provided a method for preventingor treating a bacterial infection in a subject, said infection beingcaused by bacteria producing one or more beta-lactamase enzymes, whereinthe method comprises administering to said subject a pharmaceuticallyeffective amount of: (a) a compound of Formula (I), or a stereoisomer ora pharmaceutically acceptable salt thereof, and (b) at least oneantibacterial agent or a pharmaceutically acceptable derivative thereof.

In another general aspect, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of:(a) a compound of Formula (I), or a stereoisomer or a pharmaceuticallyacceptable salt thereof, (b) at least one beta-lactamase inhibitorselected from sulbactam, tazobactam, clavulanic acid, or apharmaceutically acceptable derivative thereof, and (c) at least oneantibacterial agent or a pharmaceutically acceptable derivative thereof.

In yet another general aspect, there is provided a method for preventingor treating a bacterial infection in a subject, said infection beingcaused by bacteria producing one or more beta-lactamase enzymes, whereinthe method comprises administering to said subject a pharmaceuticallyeffective amount of: (a) a compound of Formula (I), or a stereoisomer ora pharmaceutically acceptable salt thereof, (b) at least onebeta-lactamase inhibitor selected from sulbactam, tazobactam, clavulanicacid, or a pharmaceutically acceptable derivative thereof, and (c) atleast one antibacterial agent or a pharmaceutically acceptablederivative thereof.

In another general aspect, there are provided methods for increasingantibacterial effectiveness of a antibacterial agent in a subject, saidmethod comprising co-administering said antibacterial agent or apharmaceutically acceptable derivative thereof with a pharmaceuticallyeffective amount of a compound of Formula (I) or a stereoisomer or apharmaceutically acceptable salt thereof.

The details of one or more embodiments of the invention are set forth inthe description below. Other features, objects and advantages of theinvention will be apparent from the following description includingclaims.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made to the exemplary embodiments, and specificlanguage will be used herein to describe the same. It shouldnevertheless be understood that no limitation of the scope of theinvention is thereby intended. Alterations and further modifications ofthe inventive features illustrated herein, and additional applicationsof the principles of the invention as illustrated herein, which wouldoccur to one skilled in the relevant art and having possession of thisdisclosure, are to be considered within the scope of the invention. Itmust be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the content clearly dictates otherwise. All references includingpatents, patent applications, and literature cited in the specificationare expressly incorporated herein by reference in their entirety.

The inventors have surprisingly discovered novel nitrogen containingheterocyclic compounds having antibacterial properties.

The term “C₁-C₆ alkyl” as used herein refers to branched or unbranchedacyclic hydrocarbon radical with 1 to 6 carbon atoms. Typical,non-limiting examples of “C₁-C₆ alkyl” include methyl, ethyl, n-propyl,iso-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, iso-pentyl,n-hexyl and the like. The “C₁-C₆ alkyl” may be unsubstituted, orsubstituted with one or more substituents. Typical, non-limitingexamples of such substituents include halogen, alkoxy, CN, COOH, CONH₂,OH, —NH₂, —NHCOCH₃, cycloalkyl, heterocyclyl, heteroaryl, aryl and thelike.

The term “cycloalkyl” as used herein refers to three to seven membercyclic hydrocarbon radicals. The cycloalkyl group optionallyincorporates one or more double or triple bonds, or a combination ofdouble bonds and triple bonds, but which is not aromatic. Typical,non-limiting examples of cycloalkyl groups include cyclopropane,cyclobutane, cyclopentane, cyclohexane, and cycloheptane. The cycloalkylmay be unsubstituted, or substituted with one or more substituents.Typical, non-limiting examples of such substituents include C₁-C₆ alkyl,halogen, alkoxy, CN, COOH, CONH₂, OH, NH₂, NHCOCH₃, heterocyclyl,heteroaryl, aryl, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, —OSO₂-aryl and thelike.

The term “heterocyclyl” as used herein refers to four to seven membercycloalkyl group containing one or more heteroatoms selected fromnitrogen, oxygen or sulfur. The heterocycloalkyl group optionallyincorporates one or more double or triple bonds, or a combination ofdouble bonds and triple bonds, but which is not aromatic. Typical,non-limiting examples of heterocycloalkyl groups include azetidine,pyrrolidine, 2-oxo-pyrrolidine, imidazolidin-2-one, piperidine, oxazine,thiazine, piperazine, piperazin-2,3-dione, morpholine, thiamorpholine,azapane, and the like. The heterocycloalkyl may be unsubstituted, orsubstituted with one or more substituents. Typical, non-limitingexamples of such substituents include C₁-C₆ alkyl, halogen, alkoxy, CN,COOH, CONH₂, OH, NH₂, NHCOCH₃, heterocyclyl, heteroaryl, aryl,SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, OSO₂-aryl and the like.

The term “aryl” as used herein refers to a monocyclic or polycyclicaromatic hydrocarbon. Typical, non-limiting examples of aryl groupsinclude phenyl, naphthyl, anthracenyl, fluorenyl, phenanthrenyl, and thelike. The aryl group may be unsubstituted, or substituted with one ormore substituents. Typical, non-limiting examples of such substituentsinclude C₁-C₆ alkyl, halogen, alkoxy, CN, COOH, CONH₂, OH, NH₂, NHCOCH₃,heterocyclyl, heteroaryl, aryl, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,OSO₂-aryl and the like.

The term “heteroaryl” as used herein refers to a monocyclic orpolycyclic aromatic hydrocarbon group wherein one or more carbon atomshave been replaced with heteroatoms selected from nitrogen, oxygen, andsulfur. If the heteroaryl group contains more than one heteroatom, theheteroatoms may be the same or different. Typical, non-limiting exampleof heteroaryl groups include 1,2,4-oxadiazol, 1,3,4-oxadiazol,1,3,4-thiadiazol, 1,2,3,4-tetrazol, 1,3-oxazol, 1,3-thiazole, pyridine,pyrimidine, pyrazine, pyridazine, furan, pyrrol, thiophene, imidazole,pyrazole, benzofuran, benzothiophene, benzimidazole, benzoxazole,benzothiazole, thiazole, and the like. The heteroaryl group may beunsubstituted, or substituted with one or more substituents. Typical,non-limiting examples of such substituents include C₁-C₆ alkyl, halogen,alkoxy, CN, COOH, CONH₂, OH, NH₂, NHCOCH₃, heterocyclyl, heteroaryl,aryl, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, OSO₂-aryl and the like.

The term “stereoisomers” as used herein refers to compounds that haveidentical chemical constitution, but differ with regard to thearrangement of their atoms or groups in space. The compounds of Formula(I) may contain asymmetric or chiral centers and, therefore, exist indifferent stereoisomeric forms. It is intended, unless specifiedotherwise, that all stereoisomeric forms of the compounds of Formula (I)as well as mixtures thereof, including racemic mixtures, form part ofthe present invention. In addition, the present invention embraces allgeometric and positional isomers (including cis and trans-forms), aswell as mixtures thereof, are embraced within the scope of theinvention. In general, a reference to a compound is intended to coverits stereoisomers and mixture of various stereoisomers.

The term “optionally substituted” as used herein means that substitutionis optional and therefore includes both unsubstituted and substitutedatoms and moieties. A “substituted” atom or moiety indicates that anyhydrogen on the designated atom or moiety can be replaced with aselection from the indicated substituent group, provided that the normalvalency of the designated atom or moiety is not exceeded, and that thesubstitution results in a stable compound.

The term “pharmaceutically acceptable salt” as used herein refers to oneor more salts of a given compound which possesses the desiredpharmacological activity of the free compound and which are neitherbiologically nor otherwise undesirable. In general, the“pharmaceutically acceptable salts” refer to salts that are suitable foruse in contact with the tissues of human and animals without unduetoxicity, irritation, allergic response and the like, and arecommensurate with a reasonable benefit/risk ratio. Pharmaceuticallyacceptable salts are well known in the art. For example, S. M. Berge, etal. (J. Pharmaceutical Sciences, 66: 1-19 (1977)), incorporated hereinby reference in its entirety, describes various pharmaceuticallyacceptable salts in details.

In general, the compounds according to the invention contain basic (e.g.nitrogen atoms) as well as acid moieties (e.g. compounds of Formula (I)wherein M is hydrogen). A person of skills in the art would appreciatethat such compounds, therefore, can form acidic salts (formed withinorganic and/or organic acids), as well as basic salts (formed withinorganic and/or organic bases). Such salts can be prepared usingprocedures described in the art. For example, the basic moiety can beconverted to its salt by treating a compound with a suitable amount ofacid. Typical, non-limiting examples of such suitable acids includehydrochloric acid, trifluoroacetic acid, methanesulphonic acid, or thelike. Alternatively, the acid moiety may be converted into its salt bytreating with a suitable base. Typical non-limiting examples of suchbases include sodium carbonate, sodium bicarbonate, potassium carbonate,potassium bicarbonate or the like. In case of compounds containing morethan one functional groups capable of being converted into salt, eachsuch functional group may be converted to salt independently. Forexample, in case of compounds containing two basic nitrogen atoms, onebasic nitrogen can form salt with one acid while the other basicnitrogen can form salt with another acid. Some compounds according tothe invention contain both, acidic as well as basic moieties, and thuscan form inner salts or corresponding zwitterions. In general, allpharmaceutically acceptable salt forms of compounds of Formula (I)according to invention including acid addition salts, base additionsalts, zwitterions or the like are contemplated to be within the scopeof the present invention and are generically referred to aspharmaceutically acceptable salts.

The term “halogen” or “halo” as used herein refers to chlorine, bromine,fluorine, or iodine.

The term “infection” or “bacterial infection” as used herein includespresence of bacteria, in or on a subject, which, if its growth wereinhibited, would result in a benefit to the subject. As such, the term“infection” in addition to referring to the presence of bacteria alsorefers to normal flora, which is not desirable. The term “infection”includes infection caused by bacteria.

The term “treat”, “treating” or “treatment” as used herein refers toadministering a medicament, including a pharmaceutical composition, orone or more pharmaceutically active ingredients, for prophylactic and/ortherapeutic purposes. The term “prophylactic treatment” refers totreating a subject who is not yet infected, but who is susceptible to,or otherwise at a risk of infection (preventing the bacterialinfection). The term “therapeutic treatment” refers to administeringtreatment to a subject already suffering from infection. The terms“treat”, “treating” or “treatment” as used herein also refer toadministering compositions or one or more of pharmaceutically activeingredients discussed herein, with or without additionalpharmaceutically active or inert ingredients, in order to: (i) reduce oreliminate either a bacterial infection or one or more symptoms of thebacterial infection, or (ii) retard the progression of a bacterialinfection or of one or more symptoms of the bacterial infection, or(iii) reduce the severity of a bacterial infection or of one or moresymptoms of the bacterial infection, or (iv) suppress the clinicalmanifestation of a bacterial infection, or (v) suppress themanifestation of adverse symptoms of the bacterial infection.

The term “pharmaceutically effective amount” or “therapeuticallyeffective amount” or “effective amount” as used herein refers to anamount, which has a therapeutic effect or is the amount required toproduce a therapeutic effect in a subject. For example, atherapeutically or pharmaceutically effective amount of an antibacterialagent or a pharmaceutical composition is the amount of the antibacterialagent or the pharmaceutical composition required to produce a desiredtherapeutic effect as may be judged by clinical trial results, modelanimal infection studies, and/or in vitro studies (e.g. in agar or brothmedia). The pharmaceutically effective amount depends on severalfactors, including but not limited to, the microorganism (e.g. bacteria)involved, characteristics of the subject (for example height, weight,sex, age and medical history), severity of infection and the particulartype of the antibacterial agent used. For prophylactic treatments, atherapeutically or prophylactically effective amount is that amountwhich would be effective in preventing a microbial (e.g. bacterial)infection.

The term “administration” or “administering” includes delivery of acomposition or one or more pharmaceutically active ingredients to asubject, including for example, by any appropriate methods, which servesto deliver the composition or its active ingredients or otherpharmaceutically active ingredients to the site of the infection. Themethod of administration may vary depending on various factors, such asfor example, the components of the pharmaceutical composition or thenature of the pharmaceutically active or inert ingredients, the site ofthe potential or actual infection, the microorganism involved, severityof the infection, age and physical condition of the subject and a like.Some non-limiting examples of ways to administer a composition or apharmaceutically active ingredient to a subject according to thisinvention includes oral, intravenous, topical, intrarespiratory,intraperitoneal, intramuscular, parenteral, sublingual, transdermal,intranasal, aerosol, intraocular, intratracheal, intrarectal, vaginal,gene gun, dermal patch, eye drop, ear drop or mouthwash. In case of apharmaceutical composition comprising more than one ingredient (activeor inert), one of way of administering such composition is by admixingthe ingredients (e.g. in the form of a suitable unit dosage form such astablet, capsule, solution, powder and a like) and then administering thedosage form. Alternatively, the ingredients may also be administeredseparately (simultaneously or one after the other) as long as theseingredients reach beneficial therapeutic levels such that thecomposition as a whole provides a synergistic and/or desired effect.

The term “growth” as used herein refers to a growth of one or moremicroorganisms and includes reproduction or population expansion of themicroorganism (e.g. bacteria). The term also includes maintenance ofon-going metabolic processes of a microorganism, including processesthat keep the microorganism alive.

The term, “effectiveness” as used herein refers to ability of atreatment or a composition or one or more pharmaceutically activeingredients to produce a desired biological effect in a subject. Forexample, the term “antibacterial effectiveness” of a composition or anantibacterial agent refers to the ability of the composition or theantibacterial agent to prevent or treat the microbial (e.g. bacterial)infection in a subject.

The term “synergistic” or “synergy” as used herein refers to theinteraction of two or more agents so that their combined effect isgreater than their individual effects.

The term “antibacterial agent” as used herein refers to any substance,compound or a combination of substances or a combination compoundscapable of: (i) inhibiting, reducing or preventing growth of bacteria;(ii) inhibiting or reducing ability of a bacteria to produce infectionin a subject; or (iii) inhibiting or reducing ability of bacteria tomultiply or remain infective in the environment. The term “antibacterialagent” also refers to compounds capable of decreasing infectivity orvirulence of bacteria.

The term “beta-lactam antibacterial agent” as used herein refers tocompounds with antibacterial properties and containing a beta-lactamnucleus in their molecular structure.

The term “beta-lactamase” as used herein refers to any enzyme or proteinor any other substance that breaks down a beta-lactam ring. The term“beta-lactamase” includes enzymes that are produced by bacteria and havethe ability to hydrolyze the beta-lactam ring in a beta-lactam compound,either partially or completely.

The term “beta-lactamase inhibitor” as used herein refers to a compoundcapable of inhibiting activity of one or more beta-lactamase enzymes,either partially or completely.

The term “pharmaceutically inert ingredient” or “carrier” or “excipient”refers to a compound or material used to facilitate administration of acompound, including for example, to increase the solubility of thecompound. Typical, non-limiting examples of solid carriers include,starch, lactose, dicalcium phosphate, sucrose, and kaolin and so on.Typical, non-limiting examples of liquid carriers include, sterilewater, saline, buffers, non-ionic surfactants, and edible oils such asoil, peanut and sesame oils and so on. In addition, various adjuvantscommonly used in the art may be included. These and other such compoundsare described in the literature, for example, in the Merck Index (Merck& Company, Rahway, N.J.). Considerations for inclusion of variouscomponents in pharmaceutical compositions are described, for example, inGilman et al. (Eds.) (1990); Goodman and Gilman's: The PharmacologicalBasis of Therapeutics, 8th Ed., Pergamon Press., which is incorporatedherein by reference in its entirety.

The term “subject” as used herein refers to vertebrate or invertebrate,including a mammal. The term “subject” includes human, animal, a bird, afish, or an amphibian. Typical, non-limiting examples of a “subject”includes humans, cats, dogs, horses, sheep, bovine cows, pigs, lambs,rats, mice and guinea pigs.

The term “pharmaceutically acceptable derivative” as used herein refersto and includes any pharmaceutically acceptable salt, pro-drugs,metabolites, esters, ethers, hydrates, polymorphs, solvates, complexes,enantiomers or adducts of a compound described herein which, uponadministration to a subject, is capable of providing (directly orindirectly) the parent compound. For example, the term “antibacterialagent or a pharmaceutically acceptable derivative thereof” includes allderivatives of the antibacterial agent (such as salt, pro-drugs,metabolites, esters, ethers, hydrates, polymorphs, solvates, complexes,enantiomers or adducts) which, upon administration to a subject, iscapable of providing (directly or indirectly) the antibacterialcompound.

In general, the term “cation” includes Na, K, Mg, Ca, NH₄ ⁺, (CH₃CH₂)₃N⁺etc.

In one general aspect, there are provided compounds of Formula (I):

or a stereoisomer or a pharmaceutically acceptable salt thereof;wherein:

Q is heteroaryl;

R₁ is:

-   -   (a) hydrogen,    -   (b) (CO)_(n)—R₃, or    -   (c) COOR₄,

n is 0, 1 or 2;

R₂ is:

-   -   (a) SO₃M,    -   (b) SO₂NH₂,    -   (c) PO₃M,    -   (d) CH₂COOM,    -   (e) CF₂COOM,    -   (f) CHFCOOM, or    -   (g) CF₃;

M is hydrogen or a cation;

R₃ is:

-   -   (a) hydrogen,    -   (b) C₁-C₆ alkyl optionally substituted with one or more        substituents independently selected from halogen, OR₅, CN,        COOR_(S), CONR₆R₇, NR₆R₇, NR₅COR₈, NR₅CONR₆R₇, heterocyclyl,        heteroaryl, cycloalkyl or aryl,    -   (c) CN,    -   (d) NR₆R₇,    -   (e) CONR₆R₇,    -   (f) NHCONR₆R₇,    -   (g) aryl optionally substituted with one or more substituents        independently selected from C₁-C₆ alkyl, OR₅, NR₆R₇, halogen,        CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, or        NHCONR₆R₇,    -   (h) heterocyclyl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₆R₇,    -   (i) heteroaryl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₆R₇,    -   (j) cycloalkyl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₆R₇,    -   (k) cycloalkyl substituted with C₁-C₆ alkyl wherein C₁-C₆ alkyl        is further substituted with one or more substituents        independently selected from OR₅, NR₆R₇, halogen, CN, or CONR₆R₇,        or    -   (l) OR₈;

R₄ is:

-   -   (a) hydrogen,    -   (b) C₁-C₆ alkyl optionally substituted with one or more        substituents independently selected from halogen, OR₅, CN,        COOR_(S), CONR₆R₇, NR₆R₇, NR₅COR₈, heterocyclyl, heteroaryl,        cycloalkyl or aryl,    -   (c) aryl optionally substituted with one or more substituents        independently selected from C₁-C₆ alkyl, OR₅, NR₆R₇, halogen,        CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, or        NHCONR₆R₇,    -   (d) heterocyclyl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₆R₇,    -   (e) heteroaryl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₆R₇, or    -   (f) cycloalkyl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₆R₇;

R₅ and R₈ are each independently:

-   -   (a) hydrogen, or    -   (b) C₁-C₆ alkyl optionally substituted with one or more        substituents independently selected from halogen, CN, CONR₆R₇,        NR₆R₇, heterocyclyl, heteroaryl, cycloalkyl or aryl;

R₆ and R₇ are each independently:

-   -   (a) hydrogen,    -   (b) C₁-C₆ alkyl optionally substituted with one or more        substituents independently selected from halogen, OR₅, CN,        COOR_(S), CONR₅R₈, NR₅R₈, NR₅COR₈, heterocyclyl, heteroaryl,        cycloalkyl or aryl,    -   (c) aryl optionally substituted with one or more substituents        independently selected from C₁-C₆ alkyl, OR₅, NR₅R₈, halogen,        CN, CONR₅R₈, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, or        NHCONR₅R₈,    -   (d) heterocyclyl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₅R₈, halogen, CN, CONR₅R₈, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₅R₈,    -   (e) heteroaryl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₅R₈, halogen, CN, CONR₅R₈, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₅R₈,    -   (f) cycloalkyl optionally substituted with one or more        substituents independently selected from C₁-C₆ alkyl, OR₅,        NR₅R₈, halogen, CN, CONR₅R₈, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl,        OSO₂-aryl, or NHCONR₅R₈, or    -   (g) R₆ and R₇ are joined together to form a four to seven member        ring.

Typical non-limiting examples of compounds according to the inventioninclude:

-   trans-sulfuric acid    mono-[2-(5-aminomethyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;-   trans-sulfuric acid    mono-[2-(5-((S)-1-amino-ethyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;-   trans-sulfuric acid    mono-[2-(5-((R)-1-amino-ethyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;-   trans-sulfuric acid    mono-[2-(5-(piperidin-4-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;-   trans-sulfuric acid    mono-[2-(5-((S)-pyrrolidin-2-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;-   trans-sulfuric acid    mono-[2-(5-(piperazin-1-yl-methyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;-   trans-sulfuric acid    mono-[2-(5-((RS)-1-amino-1-phenyl-methyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;-   trans-sulfuric acid    mono-[2-(5-(piperidin-4-yl)-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   trans-sulfuric acid    mono-[2-(5-((R)-piperidin-3-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-methyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-ethyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-trifluoromethyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-carboxamido-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-(isooxazol-3-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-(furan-2-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-phenyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-(pyridin-2-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-(6-carboxamido-pyridin-2-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-(5,6-dihydro-8H-imidazo[2,1-c][1,4]-oxazin-2-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-(morpholino-4-methyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of trans-sulfuric acid    mono-[2-(5-(morpholin-4-yl-carbonyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-methyl-[1,3,4]-thiadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-methyl-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-ethoxycarbonyl-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(2-methyl-2H-[1,2,3,4]-tetrazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(1-methyl-1H-[1,2,3,4]-tetrazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(3-ethoxycarbonyl-[1,2,4]-oxadiazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;-   Sodium salt of    trans-6-(sulphooxy)-2-(5-carboxamido-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;

or a stereoisomer or a pharmaceutically acceptable salt thereof.

In general, the compounds of the invention can be prepared according tothe following procedures. A person of skills in the art would appreciatethat the described methods can be varied or optimized further to providethe desired and related compounds. In the following procedures, allvariables are as defined above.

(A) Synthesis of Compounds Containing 1,3,4-Oxadiazole Groups:

In general the compounds according to the invention containing1,3,4-Oxadiazole groups were prepared using a procedure given in Scheme1.

Typically,trans-6-benzyloxy-7-oxo-1,6-diaza-bicyclo[3.2.1]octane-2-carboxylic acid(1a, which is disclosed in WO 2009/091856 A2), was reacted with alkyl oraryl or suitably substituted aryl or alkyl acid hydrazides in thepresence of a suitable coupling agent (for example, EDC hydrochloride,dicyclohexylcarbodiimide (DCC), or pivalyl chloride) in a suitablesolvent (for example, N,N dimethyl formamide, N,N dimethyl acetamide,1,4 dioxane or chloroform), and in the presence of a suitable base (forexample, N-methyl morpholine, triethylamine or diisopropyl ethylamine),and N-hydroxybenzotriazole (HOBt) at a temperature ranging from about−15° C. to 60° C., for about 1 to 24 hours to provide intermediatecompound (1b).

The cyclization of intermediate compound (1b) was effected by treatingintermediate compound (1b) with a suitable reagent such as p-toluenesulfonyl chloride, p-nitrobenzene sulfonyl chloride, or methane sulfonylchloride, in a suitable solvent (for example, toluene, chloroform,dichloromethane, or N,N-dimethyl formamide), at a temperature rangingfrom 25° C. to 110° C. for about 1 to 24 hours to obtain1,3,4-oxadiazole intermediate compound (1c). Alternatively, theintermediate compound (1c) may also be prepared by refluxingintermediate compound (1b) in toluene in presence of 4° A molecularsieves.

The 1,3,4-oxadiazole intermediate compound (1c) was subjected forhydrogenolysis by using a suitable catalyst (for example, 5% or 10%palladium on carbon or 20% palladium hydroxide on carbon), in presenceof a suitable hydrogen source (for example, hydrogen gas, ammoniumformate, or cyclohexene) in a suitable solvent (for example, methanol,ethanol, methanol-dichloromethane mixture, or N,N dimethylformamide-dichloromethane mixture) at a temperature ranging from about25° C. to 60° C. for about 1 to 24 hours to obtain intermediate compound(1d).

The intermediate compound (1d) was sulfonated by reacting it with asuitable sulfonating reagent (for example, pyridine sulfur trioxidecomplex or N,N-dimethyl formide sulfur trioxide complex) in a suitablesolvent (for example, pyridine, N,N-dimethyl formamide, dichlromethaneor mixture thereof) at a temperature ranging from about 25° C. to 80° C.for about 1 to 24 hours to provide pyridine salt of sulfonic acid whichwas subsequently treated with tetrabutyl ammonium sulfate to provideterabutylammonium salt of sulfonic acid intermediate compound (le).

Some compounds of the invention were isolated as a sodium salt bypassing intermediate compound (le) through sodium form of Aberlite 200Cresin in aqueous tetrahydrofuran followed by evaporation of solventfractions under vacuum.

Some other compounds, when R contains tert-butoxycarbonyl group oralkylsilyl group, were isolated as zwitterions by treating intermediatecompound (le) with trifluoroacetic acid in the absence of solvent or inthe presence of the solvent (for example, dichloromethane, chloroform,or acetonitrile) at a temperature ranging from about −10° C. to 40° C.,for about 1 to 14 hours.

(B) Synthesis of Compounds Containing 1,3,4-Thiadiazole Groups:

In general, the compounds according to the invention containing1,3,4-Thiadiazole were prepared using a general procedure described inScheme 2.

As per Scheme-2, trans-5-benzyloxyamino-piperidine-1,2-dicarboxylicacid-1-tert-butyl ester (2a), was reacted with alkyl or aryl or suitablysubstituted aryl or alkyl acid hydrazides in presence of a suitablecoupling agent (for example, EDC hydrochloride, dicyclohexylcarbodiimide(DCC), or pivalyl chloride), in a suitable solvent (for example, N,Ndimethyl formamide, N,N dimethyl acetamide, 1,4 dioxane or chloroform),in presence of a suitable base (for example, N-methyl morpholine,triethylamine or diisopropyl ethylamine and N-hydroxybenzotriazole(HOBt)) at a temperature ranging from about −5° C. to 60° C. for about 1to 24 hours to provide intermediate compound (2b).

The cyclization of intermediate compound (2b) was effected by treatingintermediate compound (2b) with Lowesson's reagent, in a suitablesolvent (for example, toluene, chloroform, tetrahydrofuran, orN,N-dimethyl formamide) at a temperature ranging from 25° C. to 110° C.,for about 1 to 24 hours to provide 1,3,4-thiadiazole intermediatecompound (2c).

The intermediate compound (2c) was deprotected to provide intermediatecompound (2d), using deprotecting agent such as trifluoro acetic acid orhydrochloric acid in a solvent such as dichloromethane, chloroform,acetonitrile, or water at a temperature ranging from about −5° C. to 50°C. for about 1 to 24 hours.

The cyclization of intermediate compound (2d) was achieved by treatingintermediate compound (2d) using a suitable reagent (for example,phosgene solution, diphosgene or triphosgene) in a suitable solvent (forexample, toluene, chloroform, acetonitrile and in presence of a suitablebase (for example, triethyl amine, or diisopropyl ethyl amine,N,N-dimethylamino pyridine) at a temperature ranging from about −5° C.to 50° C. for about 1 to 24 hours to provide cyclized intermediatecompound (2e).

The cyclized intermediate compound (2e) was subjected for hydrogenolysisby using a suitable catalyst (for example, 5% or 10% palladium oncarbon, or 20% palladium hydroxide on carbon) in presence of a suitablehydrogen source (for example, hydrogen gas, ammonium formate, orcyclohexene) in a suitable solvent (for example, methanol, ethanol,methanol-dichloromethane mixture, or N,N dimethyl formamidedichloromethane mixture), at a temperature ranging from 25° C. to 60° C.for about 1 to 24 hours to provide N-hydroxy intermediate compound (2f).

The intermediate compound (2f) was sulfonated by reacting it with asuitable sulfonating reagent (for example, pyridine sulfur trioxidecomplex, or N,N-dimethyl formamide sulfur trioxide complex) in asuitable solvent (for example, pyridine, N,N-dimethyl formamide,dichloromethane or mixture thereof) at a temperature ranging from about0° C. to 50° C. for about 1 to 24 hours to provide pyridine salt ofsulfonic acid which was subsequently treated with tetrabutyl ammoniumacetate to provide terabutylammonium salt of sulfonic acid intermediatecompound (2g).

The compound of invention was isolated as a sodium salt by passingintermediate compound (2g) through sodium form of Aberlite SR-L resin inaqueous tetrahydrofuran followed by evaporation of solvent fractionsunder vacuum. Alternatively, when R contains tert-butoxycarbonyl groupor alkylsilyl group, then compound of invention was isolated aszwitterions by treating intermediate compound (2g) with trifluoroaceticacid in absence of solvent or in the presence of a suitable solvent (forexample, dichloromethane, chloroform, or acetonitrile) at a temperatureranging from about −10° C. to 40° C. for about 1 to 14 hours.

(C) Synthesis of Compounds Containing 1,2,4-Oxadiazol-3-Yl Groups:

In general, the compound according to the invention containing1,2,4-Oxadiazol-3-yl groups was prepared using a general proceduredescribed in Scheme 3.

As per Scheme-3, trans-5-benzyloxyamino-piperidine-1,2-dicarboxylicacid-1-tert-butyl ester compound (2a), was reacted with a suitable acidchloride (for example, pivolyl chloride) in presence of a suitable base(for example, N-methyl morpholine, triethylamine, diisopropylethylamine) in a suitable solvent (for example, dichloromethane,tetrahydrofuran, 1,4 dioxane or chloroform), at a temperature rangingfrom about −5° C. to 35° C., for about 1 to 2 hours to provide anhydridewhich was subsequently treated with ammonia gas at a temperature rangingfrom about −50° C. to 5° C. for about 0.5 to 2 hours to provide amideintermediate compound (3b).

Dehydration of the intermediate compound (3b) was effected by treatingintermediate (3b) with trifluoroacetic anhydride, in a suitable solvent(for example, toluene, chloroform, tetrahydrofuran, or dichloromethane),at a temperature ranging from about −5° C. to 35° C., for about 1 to 24hours to provide the nitrile intermediate compound (3c).

The intermediate compound (3c) was reacted with hydroxylaminehydrochloride in a suitable solvent (for example, methanol, water,ethanol, or mixture thereof), at a temperature ranging from about −5° C.to 35° C., for about 1 to 24 hours to provide the amidoxime intermediatecompound (3d).

The intermediate compound (3d) was reacted with suitably substitutedalkyl anhydride in a suitable solvent (for example, dichloromethane,chloroform, tetrahydrofuran, or mixture thereof), and in presence of asuitable base (for example, N-methyl morpholine, triethylamine, ordiisopropyl ethylamine) at a temperature ranging from about −5° C. to35° C., for about 1 to 24 hours to provide the O-acylated amidoximeintermediate compound (3e).

Cyclization of the intermediate compound (3e) was affected by refluxingintermediate compound (3e) in pyridine for about 1 to 24 hours toprovide the cyclized intermediate compound (3f).

The intermediate compound (3f) was deprotected to provide intermediatecompound (3g), using a suitable deprotecting agent (for example,trifluoro acetic acid, or hydrochloric acid) in a suitable solvent (forexample, dichloromethane, chloroform, acetonitrile or water), at atemperature ranging from about −25° C. to 50° C. for about 1 to 24hours.

The cyclization of intermediate compound (3g) was achieved by treatingintermediate compound (3g) with a suitable reagent (for example,phosgene solution, diphosgene or triphosgene) in a suitable solvent (forexample, toluene, chloroform, or acetonitrile), and in presence of asuitable base (for example, triethyl amine or diisopropyl ethyl amine)at a temperature ranging from about −5° C. to 50° C. for about 1 to 24hours to provide the cyclized intermediate compound (3h).

The cyclized intermediate compound (3h) was subjected for hydrogenolysisusing a suitable catalyst (for example, 5% or 10% palladium on carbon,or 20% palladium hydroxide on carbon) in presence of a suitable hydrogensource (for example, hydrogen gas, ammonium formate, or cyclohexene) ina suitable solvent (for example, methanol, ethanol,methanol-dichloromethane mixture, or N,N dimethyl formamidedichloromethane mixture) at a temperature ranging from about 25° C. to60° C., for about 1 to 24 hours to provide N-hydroxy intermediatecompound (3i).

The intermediate compound (3i) was sulfonated by reacting it with asuitable sulfonating reagent (for example, pyridine sulfur trioxidecomplex, or N,N-dimethyl formamide sulfur trioxide complex) in asuitable solvent (for example, pyridine, N,N-dimethyl formamide,dichloromethane or a mixture thereof), at a temperature ranging fromabout −5° C. to 50° C., 0.5 to 24 hours to provide pyridine salt ofsulfonic acid which subsequently was treated with tetrabutyl ammoniumacetate to provide terabutylammonium salt of sulfonic acid intermediatecompound (3j).

The compound of the invention was isolated as a sodium salt by passingintermediate compound (3j) through sodium form of Dowex 50WX8 200 resinin aqueous tetrahydrofuran followed by evaporation of solvent fractionsunder vacuum.

Alternatively, when R contains tert-butoxycarbonyl group or alkylsilylgroup then compound of the invention was isolated as zwitterions bytreating intermediate compound (3j) with trifluoroacetic acid in theabsence of solvent or in the presence of the solvent (for example,dichloromethane, chloroform, or acetonitrile) at a temperature rangingfrom −10° C. to 40° C. for about 1 to 14 hours.

(D) Synthesis of Compounds Containing 1,2,3,4-Tetrazol Groups:

As per Scheme-4, trans-5-benzyloxyamino-2-cyano-piperidine-1-carboxylicacid-1-tert-butyl ester compound (3c), was reacted sodium azide inpresence of triethylamine hydrochloride, in a suitable solvent (forexample, toluene, or xylene) at a reflux temperature for about 1 to 12hours to provide tetrazole intermediate compound (4b).

Alkylation of the intermediate compound (4b) was effected by treatingintermediate compound (4b) with suitable alkyl halide in a suitablesolvent (for example, N,N-dimethyl formamide, N,N-dimethyl acetamide,tetrahydrofuran) and in the presence of a suitable base (for example,cesium carbonate, potassium carbonate or sodium carbonate) at atemperature ranging from about −5° C. to 35° C. for about 1 to 24 hoursto provide isomeric mixture of N-alkyl tetrazol intermediate compounds(4c) and (4c′), which was separated using column chromatographytechnique to provide isomerically pure compound (4c) and (4c′) andhitherto the pure intermediate is referred as compound (4d).

The intermediate compound (4d) was deprotected to provide intermediatecompound (4e), using a suitable deprotecting agent (trifluoro aceticacid or hydrochloric acid), in a suitable solvent (for example,dichloromethane, chloroform, acetonitrile or water), at a temperatureranging from about −25° C. to 50° C., for about 1 to 24 hours.

The cyclization of intermediate compound (4e) was achieved by treatingintermediate compound (4e) using a suitable reagent (for example,phosgene solution, diphosgene or triphosgene) in a suitable solvent (forexample, toluene, chloroform, or acetonitrile) in the presence of asuitable base (for example, triethyl amine or diisopropyl ethyl amine)and N,N-dimethylamino pyridine at a temperature ranging from about −5°C. to 50° C. for about 1 to 24 hours to provide cyclized intermediatecompound (4f).

The cyclized intermediate compound (4f) was subjected for hydrogenolysisby using a suitable catalyst (for example, 5% or 10% palladium on carbonor 20% palladium hydroxide on carbon) in presence of a suitable hydrogensource (for example, hydrogen gas, ammonium formate, or cyclohexene) ina suitable solvent (for example, methanol, ethanol, methanol-ethylacetate mixture, or N,N dimethyl formamide-dichloromethane mixture) at atemperature ranging from about 25° C. to 60° C., for 1 to 24 hours toprovide N-hydroxy intermediate compound (4g).

The intermediate compound (4g) was sulfonated by reacting it with asuitable sulfonating reagent such (for example, pyridine sulfur trioxidecomplex, or N,N-dimethyl formamide sulfur trioxide complex) in asuitable solvent (for example, pyridine, N,N-dimethyl formamide,dichloromethane or mixture thereof) at a temperature ranging from about−5° C. to 50° C. for about 0.5 to 24 hours to provide pyridine salt ofsulfonic acid which subsequently was treated with tetrabutyl ammoniumacetate to provide terabutylammonium salt of sulfonic acid intermediatecompound (4h).

The compound of invention was isolated as a sodium salt by passingintermediate 4h through sodium form of Dowex 50WX8 200 resin in aqueoustetrahydrofuran followed by evaporation of solvent fractions undervacuum. Alternatively, when R contains tert-butoxycarbonyl group oralkylsilyl group then compound of invention was isolated as zwitterionsby treating intermediate 4h with trifluoroacetic acid in the absence ofsolvent or in the presence of a suitable solvent (for example,dichloromethane, chloroform, or acetonitrile) at a temperature rangingfrom about −10° C. to 40° C. for about 1 to 14 hours.

(E) Synthesis of Compounds Containing 1,2,4-Oxadiazol-5-Yl Groups:

In general, the compounds according to the invention containing1,2,4-Oxadiazol-5-yl groups were prepared using a general proceduredescribed in Scheme 5.

As per Scheme-5,trans-6-benzyloxy-7-oxo-1,6-diaza-bicyclo[3.2.1]octane-2-carboxylic acidcompound (1a), was reacted with suitably substituted aryl or alkylamidoxime in the presence of a suitable coupling agent (for example, EDChydrochloride, dicyclohexylcarbodiimide (DCC), or pivalyl chloride) in asuitable solvent (for example N,N dimethyl formamide, N,N dimethylacetamide, 1,4 dioxane or chloroform) and in presence of a suitable base(for example, N-methyl morpholine, triethylamine or diisopropylethylamine) and N-hydroxybenzotriazole (HOBt) at a temperature rangingfrom about −5° C. to 60° C., for about 1 to 24 hours to provideintermediate compound (5b).

The cyclization of intermediate compound (5b) was achieved by refluxingintermediate compound (5b) in pyridine for about 1 to 24 hours toprovide cyclized intermediate compound (5c).

The cyclized intermediate compound (5c) was subjected for hydrogenolysisby using a suitable catalyst (for example, 5% or 10% palladium oncarbon, or 20% palladium hydroxide on carbon) in presence of a suitablehydrogen source (for example, hydrogen gas, ammonium formate, orcyclohexene) in a suitable solvent (for example, methanol, ethanol,methanol-ethyl acetate mixture, N,N dimethyl formamide dichloromethanemixture) at a temperature ranging from about 25° C. to 60° C. for about1 to 24 hours to provide N-hydroxy intermediate compound (5d).

The intermediate compound (5d) was sulfonated by reacting it with asuitable sulfonating reagent (for example, pyridine sulfur trioxidecomplex, or N,N-dimethyl formamide sulfur trioxide complex) in asuitable solvent (for example, pyridine, N,N-dimethyl formamide,dichloromethane or a mixture thereof) at a temperature ranging fromabout −5° C. to 50° C. for about 0.5 to 24 hours to provide pyridinesalt of sulfonic acid which subsequently was treated with tetrabutylammonium acetate to provide terabutylammonium salt of sulfonic acidintermediate compound (5e).

The compound of invention was isolated as a sodium salt by passingintermediate 5e through sodium form of Amberlite 200C resin in aqueoustetrahydrofuran followed by evaporation of solvent fractions undervacuum. Alternatively, when R contains tert-butoxycarbonyl group oralkylsilyl group then compound of invention was isolated as zwitterionsby treating intermediate (5e) with trifluoroacetic acid in the absenceof solvent or in the presence of a suitable solvent (for example,dichloromethane, chloroform, or acetonitrile) at a temperature rangingfrom about −10° C. to 40° C. for about 1 to 14 hours.

In some embodiments, there are provided pharmaceutical compositionscomprising a compound of Formula (I), or a stereoisomer or apharmaceutically acceptable salt thereof.

In some other embodiments, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of acompound of Formula (I) or a stereoisomer or a pharmaceuticallyacceptable salt thereof.

In some embodiments, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, wherein themethod comprises administering to said subject a pharmaceuticallyeffective amount of a compound of Formula (I) or a stereoisomer or apharmaceutically acceptable salt thereof.

In some other embodiments, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of apharmaceutical composition comprising a compound of Formula (I) or astereoisomer or a pharmaceutically acceptable salt thereof.

In some other embodiments, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, wherein themethod comprises administering to said subject a pharmaceuticallyeffective amount of a pharmaceutical composition comprising a compoundof Formula (I) or a stereoisomer or a pharmaceutically acceptable saltthereof.

In some embodiments, there are provided pharmaceutical compositionscomprising: (a) a compound of Formula (I), or a stereoisomer or apharmaceutically acceptable salt thereof, and (b) at least onebeta-lactamase inhibitor selected from sulbactam, tazobactam, clavulanicacid, or a pharmaceutically acceptable derivative thereof.

In some other embodiments, there are provided pharmaceuticalcompositions comprising: (a) a compound of Formula (I), or astereoisomer or a pharmaceutically acceptable salt thereof, and (b) atleast one antibacterial agent or a pharmaceutically acceptablederivative thereof.

In some other embodiments, there are provided pharmaceuticalcompositions comprising: (a) a compound of Formula (I), or astereoisomer or a pharmaceutically acceptable salt thereof, (b) at leastone beta-lactamase inhibitor selected from sulbactam, tazobactam,clavulanic acid, or a pharmaceutically acceptable derivative thereof,and (c) at least one antibacterial agent or a pharmaceuticallyacceptable derivative thereof.

In some other embodiments, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of apharmaceutical composition comprising: (a) a compound of Formula (I), ora stereoisomer or a pharmaceutically acceptable salt thereof, and (b) atleast one beta-lactamase inhibitor selected from sulbactam, tazobactam,clavulanic acid, or a pharmaceutically acceptable derivative thereof.

In some other embodiments, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, wherein themethod comprises administering to said subject a pharmaceuticallyeffective amount of a pharmaceutical composition comprising: (a) acompound of Formula (I), or a stereoisomer or a pharmaceuticallyacceptable salt thereof, and (b) at least one beta-lactamase inhibitorselected from sulbactam, tazobactam, clavulanic acid, or apharmaceutically acceptable derivative thereof.

In some other embodiments, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of apharmaceutical composition comprising: (a) a compound of Formula (I), ora stereoisomer or a pharmaceutically acceptable salt thereof, and (b) atleast one antibacterial agent or a pharmaceutically acceptablederivative thereof.

In some other embodiments, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, wherein themethod comprises administering to said subject a pharmaceuticallyeffective amount of a pharmaceutical composition comprising: (a) acompound of Formula (I), or a stereoisomer or a pharmaceuticallyacceptable salt thereof, and (b) at least one antibacterial agent or apharmaceutically acceptable derivative thereof.

In some other embodiments, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of apharmaceutical composition comprising: (a) a compound of Formula (I), ora stereoisomer or a pharmaceutically acceptable salt thereof, (b) atleast one beta-lactamase inhibitor selected from sulbactam, tazobactam,clavulanic acid, or a pharmaceutically acceptable derivative thereof,and (c) at least one antibacterial agent or a pharmaceuticallyacceptable derivative thereof.

In some other embodiments, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, wherein themethod comprises administering to said subject a pharmaceuticallyeffective amount of a pharmaceutical composition comprising: (a) acompound of Formula (I), or a stereoisomer or a pharmaceuticallyacceptable salt thereof, (b) at least one beta-lactamase inhibitorselected from sulbactam, tazobactam, clavulanic acid, or apharmaceutically acceptable derivative thereof, and (c) at least oneantibacterial agent or a pharmaceutically acceptable derivative thereof.

In some other embodiments, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of:(a) a compound of Formula (I), or a stereoisomer or a pharmaceuticallyacceptable salt thereof, and (b) at least one beta-lactamase inhibitorselected from sulbactam, tazobactam, clavulanic acid, or apharmaceutically acceptable derivative thereof.

In some other embodiments, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, wherein themethod comprises administering to said subject a pharmaceuticallyeffective amount of: (a) a compound of Formula (I), or a stereoisomer ora pharmaceutically acceptable salt thereof, and (b) at least onebeta-lactamase inhibitor selected from sulbactam, tazobactam, clavulanicacid, or a pharmaceutically acceptable derivative thereof.

In some other embodiments, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of:(a) a compound of Formula (I), or a stereoisomer or a pharmaceuticallyacceptable salt thereof, and (b) at least one antibacterial agent or apharmaceutically acceptable derivative thereof.

In some other embodiments, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, wherein themethod comprises administering to said subject a pharmaceuticallyeffective amount of: (a) a compound of Formula (I), or a stereoisomer ora pharmaceutically acceptable salt thereof, and (b) at least oneantibacterial agent or a pharmaceutically acceptable derivative thereof.

In some other embodiments, there is provided a method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of:(a) a compound of Formula (I), or a stereoisomer or a pharmaceuticallyacceptable salt thereof, (b) at least one beta-lactamase inhibitorselected from sulbactam, tazobactam, clavulanic acid, or apharmaceutically acceptable derivative thereof, and (c) at least oneantibacterial agent or a pharmaceutically acceptable derivative thereof.

In some other embodiments, there is provided a method for preventing ortreating a bacterial infection in a subject, said infection being causedby bacteria producing one or more beta-lactamase enzymes, wherein themethod comprises administering to said subject a pharmaceuticallyeffective amount of: (a) a compound of Formula (I), or a stereoisomer ora pharmaceutically acceptable salt thereof, (b) at least onebeta-lactamase inhibitor selected from sulbactam, tazobactam, clavulanicacid, or a pharmaceutically acceptable derivative thereof, and (c) atleast one antibacterial agent or a pharmaceutically acceptablederivative thereof.

In some embodiments, there are provided methods for increasingantibacterial effectiveness of a antibacterial agent in a subject, saidmethod comprising co-administering said antibacterial agent or apharmaceutically acceptable derivative thereof with a pharmaceuticallyeffective amount of a compound of Formula (I) or a stereoisomer or apharmaceutically acceptable salt thereof.

In some embodiments, the compositions and methods according to theinvention use compounds of Formula (I) or a stereoisomer or apharmaceutically acceptable salt thereof in combination with at leastone antibacterial agent or a pharmaceutically acceptable derivativethereof. A wide variety of antibacterial agents can be used. Typical,non-limiting examples of antibacterial agents include one or more ofantibacterial compounds generally classified as aminoglycosides,Ansamycins, Carbacephems, Cephalosporins, Cephamycins, Lincosamides,Lipopeptides, Macrolides, Monobactams, Nitrofurans, Penicillins,Polypeptides, Quinolones, Sulfonamides, Tetracyclines, Oxazolidinone andthe like.

Typical, non-limiting examples of Aminoglycoside antibacterial agentsinclude Amikacin, Gentamicin, Kanamycin, Neomycin, Netilmicin,Tobramycin, Paromomycin, Arbekacin, Streptomycin, Apramycin and thelike.

Typical, non-limiting examples of Ansamycin antibacterial agents includeGeldanamycin, Herbimycin and the like.

Typical, non-limiting examples of Carbacephem antibacterial agentsinclude Loracarbef and the like.

Typical, non-limiting examples of Carbapenem antibacterial agentsinclude Ertapenem, Doripenem, Imipenem, Meropenem and the like.

Typical, non-limiting examples of Cephalosporin and Cephamycinantibacterial agents include Cefazolin, Cefacetrile, Cefadroxil,Cefalexin, Cefaloglycin, Cefalonium, Cefaloridine, Cefalotin, Cefapirin,Cefatrizine, Cefazedone, Cefazaflur, Cefradine, Cefroxadine, Ceftezole,Cefaclor, Cefamandole, Cefminox, Cefonicid, Ceforanide, Cefotiam,Cefprozil, Cefbuperazone, Cefuroxime, Cefuzonam, Cephamycin, Cefoxitin,Cefotetan, Cefmetazole, Carbacephem, Cefixime, Ceftazidime, Ceftriaxone,Cefcapene, Cefdaloxime, Cefdinir, Cefditoren, Cefetamet, Cefmenoxime,Cefodizime, Cefoperazone, Cefotaxime, Cefpimizole, Cefpiramide,Cefpodoxime, Cefsulodin, Cefteram, Ceftibuten, Ceftiolene, Ceftizoxime,Oxacephem, Cefepime, Cefozopran, Cefpirome, Cefquinome, Ceftobiprole,Ceftiofur, Cefquinome, Cefovecin, CXA-101, Ceftaroline, Ceftobiproleetc.

Typical, non-limiting examples of Lincosamide antibacterial agentsinclude Clindamycin, Lincomycin and the like.

Typical, non-limiting examples of Macrolide antibacterial agents includeAzithromycin, Clarithromycin, Dirithromycin, Erythromycin,Roxithromycin, Troleandomycin, Telithromycin, Spectinomycin,Solithromycin and the like.

Typical, non-limiting examples of Monobactam antibacterial agentsinclude Aztreonam and the like.

Typical, non-limiting examples of Nitrofuran antibacterial agentsinclude Furazolidone, Nitrofurantoin and the like.

Typical, non-limiting examples of Penicillin antibacterial agentsinclude Amoxicillin, Ampicillin, Azlocillin, Carbenicillin, Cloxacillin,Dicloxacillin, Flucloxacillin, Mezlocillin, Methicillin, Nafcillin,Oxacillin, Penicillin G, Penicillin V, Piperacillin, Temocillin,Ticarcillin and the like.

Typical, non-limiting examples of Polypeptide antibacterial agentsinclude Bacitracin, Colistin, Polymyxin B and the like.

Typical, non-limiting examples of Quinolone antibacterial agents includeCiprofloxacin, Enoxacin, Gatifloxacin, Levofloxacin, Lomefloxacin,Moxifloxacin, Nalidixic acid, Levonadifloxacin, Norfloxacin, Ofloxacin,Trovafloxacin, Grepafloxacin, Sparfloxacin, Temafloxacin and the like.

Typical, non-limiting examples of Sulfonamide antibacterial agentsinclude Mafenide, Sulfonamidochrysoidine, Sulfacetamide, Sulfadiazine,Sulfamethizole, Sulfamethoxazole, Sulfasalazine, Sulfisoxazole,Trimethoprim and the like.

Typical, non-limiting examples of Tetracycline antibacterial agentsinclude Demeclocycline, Doxycycline, Minocycline, Oxytetracycline,Tetracycline, Tigecycline and the like.

Typical, non-limiting examples of Oxazolidinone antibacterial agentsinclude Tedizolid, Linezolid, Ranbezolid, Torezolid, Radezolid etc.

The pharmaceutical compositions according to the invention may includeone or more pharmaceutically acceptable carriers or excipients or thelike, Typical, non-limiting examples of such carriers or excipientinclude mannitol, lactose, starch, magnesium stearate, sodiumsaccharine, talcum, cellulose, sodium crosscarmellose, glucose, gelatin,sucrose, magnesium carbonate, wetting agents, emulsifying agents,solubilizing agents, pH buffering agents, lubricants, stabilizingagents, binding agents etc.

The pharmaceutical compositions according to this invention can exist invarious forms. In some embodiments, the pharmaceutical composition is inthe form of a powder or a solution. In some other embodiments, thepharmaceutical compositions according to the invention are in the formof a powder that can be reconstituted by addition of a compatiblereconstitution diluent prior to parenteral administration. Non-limitingexample of such a compatible reconstitution diluent includes water.

In some other embodiments, the pharmaceutical compositions according tothe invention are in the form of a frozen composition that can bediluted with a compatible diluent prior to parenteral administration.

In some other embodiments, the pharmaceutical compositions according tothe invention are in the form ready to use for parenteraladministration.

In the methods according to the invention, the pharmaceuticalcomposition and/or other pharmaceutically active ingredients disclosedherein may be administered by any appropriate method, which serves todeliver the composition or its constituents or the active ingredients tothe desired site. The method of administration can vary depending onvarious factors, such as for example, the components of thepharmaceutical composition and nature of the active ingredients, thesite of the potential or actual infection, the microorganism (e.g.bacteria) involved, severity of infection, age and physical condition ofthe subject. Some non-limiting examples of administering the compositionto a subject according to this invention include oral, intravenous,topical, intrarespiratory, intraperitoneal, intramuscular, parenteral,sublingual, transdermal, intranasal, aerosol, intraocular,intratracheal, intrarectal, vaginal, gene gun, dermal patch, eye drop,ear drop or mouthwash.

The compositions according to the invention can be formulated intovarious dosage forms wherein the active ingredients and/or excipientsmay be present either together (e.g. as an admixture) or as separatecomponents. When the various ingredients in the composition areformulated as a mixture, such composition can be delivered byadministering such a mixture. The composition or dosage form wherein theingredients do not come as a mixture, but come as separate components,such composition/dosage form may be administered in several ways. In onepossible way, the ingredients may be mixed in the desired proportionsand the mixture is then administered as required. Alternatively, thecomponents or the ingredients (active or inert) may be separatelyadministered (simultaneously or one after the other) in appropriateproportion so as to achieve the same or equivalent therapeutic level oreffect as would have been achieved by administration of the equivalentmixture.

Similarly, in the methods according to the invention, the activeingredients disclosed herein may be administered to a subject in severalways depending on the requirements. In some embodiments, the activeingredients are admixed in appropriate amounts and then the admixture isadministered to a subject. In some other embodiments, the activeingredients are administered separately. Since the inventioncontemplates that the active ingredients agents may be administeredseparately, the invention further provides for combining separatepharmaceutical compositions in kit form. The kit may comprise one ormore separate pharmaceutical compositions, each comprising one or moreactive ingredients. Each of such separate compositions may be present ina separate container such as a bottle, vial, syringes, boxes, bags, andthe like. Typically, the kit comprises directions for the administrationof the separate components. The kit form is particularly advantageouswhen the separate components are preferably administered in differentdosage forms (e.g., oral and parenteral) ore are administered atdifferent dosage intervals. When the active ingredients are administeredseparately, they may be administered simultaneously or sequentially.

The pharmaceutical composition or the active ingredients according tothe present invention may be formulated into a variety of dosage forms.Typical, non-limiting examples of dosage forms include solid,semi-solid, liquid and aerosol dosage forms; such as tablets, capsules,powders, solutions, suspensions, suppositories, aerosols, granules,emulsions, syrups, elixirs and a like.

In general, the pharmaceutical compositions and method disclosed hereinare useful in preventing or treating bacterial infections.Advantageously, the compositions and methods disclosed herein are alsoeffective in preventing or treating infections caused by bacteria thatare considered be less or not susceptible to one or more of knownantibacterial agents or their known compositions. Some non-limitingexamples of such bacteria known to have developed resistance to variousantibacterial agents include Acinetobacter, E. coli, Pseudomonasaeruginosa, Staphylococcus aureus, Enterobacter, Klebsiella, Citrobacterand a like. Other non-limiting examples of infections that may beprevented or treated using the compositions and/or methods of theinvention include: skin and soft tissue infections, febrile neutropenia,urinary tract infection, intraabdominal infections, respiratory tractinfections, pneumonia (nosocomial), bacteremia meningitis, surgical,infections etc.

Surprisingly, the compounds, compositions and methods according to theinvention are also effective in preventing or treating bacterialinfections that are caused by bacteria producing one or morebeta-lactamase enzymes. The ability of compositions and methodsaccording to the present invention to treat such resistant bacteria withtypical beta-lactam antibiotics represents a significant improvement inthe art.

In general, the compounds of Formula (I) or a stereoisomer orpharmaceutically acceptable salt thereof according to invention are alsouseful in increasing antibacterial effectiveness of a antibacterialagent in a subject. The antibacterial effectiveness of one or moreantibacterial agents may increased, for example, by co-administeringsaid antibacterial agent or a pharmaceutically acceptable salt thereofwith a pharmaceutically effective amount of a compound of Formula (I) ora stereoisomer or a pharmaceutically acceptable salt thereof accordingto the invention.

It will be readily apparent to one skilled in the art that varyingsubstitutions and modifications may be made to the invention disclosedherein without departing from the scope and spirit of the invention. Forexample, those skilled in the art will recognize that the invention maybe practiced using a variety of different compounds within the describedgeneric descriptions.

EXAMPLES

The following examples illustrate the embodiments of the invention thatare presently best known. However, it is to be understood that thefollowing are only exemplary or illustrative of the application of theprinciples of the present invention. Numerous modifications andalternative compositions, methods, and systems may be devised by thoseskilled in the art without departing from the spirit and scope of thepresent invention. The appended claims are intended to cover suchmodifications and arrangements. Thus, while the present invention hasbeen described above with particularity, the following examples providefurther detail in connection with what are presently deemed to be themost practical and preferred embodiments of the invention.

Example-1 Sodium salt oftrans-6-(sulphooxy)-2-(5-methyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

Step-1: Preparation oftrans-6-benzyloxy-7-oxo-1,6-diaza-bicyclo[3.2.1]octane-2-carboxylic acidN′-acetyl hydrazide

To a mixture of acetic acid hydrazide (1.47 gm, 19.9 mmol) andtrans-6-benzyloxy-7-oxo-1,6-diaza-bicyclo[3.2.1]octane-2-carboxylic acid(5 gm, 18.1 mmol) in N,N-dimethyl formamide (50 ml), was added EDChydrochloride (5.19 gm, 27.1 mmol), DIPEA (9.50 ml, 54.3 mmol) and HOBt(3.66 gm, 27.1 mmol). The reaction mixture was stirred at a temperaturebetween 25° C. to 35° C. for 14 hours. It was diluted with water (250ml) and extracted with ethyl acetate (75 ml×3). The combined organicextract was washed with water, saturated aqueous sodium chloridesolution (100 ml) and layers were separated. The organic layer wasconcentrated in vacuum to provide the crude compound, which wassubjected for silica gel column chromatography using methanol chloroformto provide Step-1 product (2.2 gm) in 33% yield as powder.

Analysis:

MS (ES+) C₁₆H₂₀N₄O₄=333.2 (M+1);

H¹NMR (CDCl₃)=8.52 (s, 1H), 7.67 (s, 1H), 7.35-7.43 (m, 5H), 5.05 (d,1H), 4.91 (d, 1H), 4.01 (d, 1H), 3.21 (br d, 1H), 3.04-3.15 (m, 2H),2.30-2.35 (m, 1H), 2.02 (s, 3H), 1.89-2.05 (m, 3H).

Step-2: Preparation oftrans-6-benzyloxy-2-(5-methyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

The product as obtained in Step-1 (2 gm, 6.0 mmol) in chloroform (30 ml)was added diisopropylethylamine (3 ml, 17.4 mmol) followed by p-toluenesulfonyl chloride (1.72 gm, 9.0 mmol). The reaction mixture was refluxeduntil TLC showed complete consumption of starting material. As thereaction was completed, the water (50 ml) was added, and the mixture wasextracted with chloroform (50 ml×2) and layers were separated. Theorganic layer was concentrated in vacuum to provide crude compound thatwas subjected to silica gel column chromatography to provide cyclizedStep-2 product as a powder (1.25 gm) in 80% yield.

Analysis:

MS (ES+) C₁₆H₁₈N₄O₃=315.2 (M+1);

H¹NMR (CDCl₃)=7.25-7.44 (m, 5H), 4.08 (d, 1H), 4.23 (d, 1H), 4.69 (t,1H), 3.36 (br t, 1H), 2.90-2.94 (m, 1H), 2.80 (d, 1H), 2.54 (s, 3H),2.26-2.31 (m, 2H), 2.10-2.12 (m, 1H), 1.94-1.98 (m, 1H).

Step-3: Preparation oftrans-6-hydroxy-2-(5-methyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

The Step-2 product (1.2 gm, 3.8 mmol) and 10% palladium on carbon (300mg) in methanol (25 ml) was stirred under atmospheric hydrogen pressureat a temperature of 30° C. for 4 hours. As TLC indicated completion ofreaction, the catalyst was filtered over a celite bed andcatalyst-containing bed was washed with additional methanol. Thefiltrate was concentrated in vacuum to provide a white powder compoundin 0.82 gm quantity as a Step-3 product in 80% yield.

Analysis:

MS (ES+) C₉H₁₂N₄O₃=225.1 (M+1);

H¹NMR (DMSO-d⁶)=9.84 (s, 1H), 4.54 (d, 1H), 3.63 (br s, 1H), 2.92 (br d,1H), 2.69 (d, 1H), 2.48 (s, 3H), 1.98-2.16 (m, 3H), 1.81-1.88 (m, 1H).

Step-4: Preparation of tetrabutylammonium salt oftrans-6-sulphooxy-2-(5-methyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

Product as obtained in Step-3 (0.82 gm, 3.66 mmol) was dissolved inpyridine (8.2 ml) and to the clear solution was added pyridine sulfurtrioxide complex (2.91 gm, 18.3 mmol). The suspension was stirred at atemperature of 35° C. for overnight. The suspension was filtered and thesolids were washed with dichloromethane (10 ml×2). The filtrate wasevaporated under vacuum and the residue was dissolved in 0.5N aqueouspotassium dihydrogen phosphate solution (50 ml) for 0.5 hour. Thesolution was washed with dichloromethane (30 ml) and layers wereseparated. To the aqueous layer was added tetrabutylammonium sulphate(1.23 gm, 3.66 mmol) and stirred for two hours at 25° C. As TLC showedcompletion of reaction, the solution was extracted with dichloromethane(50 ml×2). The combined organic layer was dried on Na₂SO₄ and evaporatedunder vacuum to provide white solid as a Step-4 product (1.95 gm) in 80%yield.

Analysis:

MS (ES−) C₉H₁₂N₄O₆S.N(C₄H₉)₄ as a salt=303.2 (M−1) as a free sulfonicacid;

H¹NMR (CDCl₃)=4.65 (d, 1H), 4.39 (br s, 1H), 3.23-3.31 (m, 8H), 2.84 (d,1H), 2.54 (s, 3H), 2.21-2.34 (m, 3H), 1.98-2.01 (m, 1H), 1.49-1.70 (m,8H), 1.29-1.49 (m, 8H), 0.95 (t, 12H).

Step-5: Sodium salt oftrans-6-sulphooxy-2-(5-methyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

The compound (0.546 gm) obtained as a Step-4 product was loaded intetrahydrofuran and water 1:9 mixture (10 ml) and passed slowly throughfreshly activated sodium form of Amberlite 200C resin (50 gm). Thefractions were analyzed on TLC and combined fractions were evaporated toremove lower boiling solvent under vacuum below 40° C. The aqueous layerwas then washed with dichloromethane (10 ml×2) and layers wereseparated. The aqueous layer was concentrated under vacuum below 40° C.to provide residue which was triturated with acetone. The solid wasobtained to provide Example-1 compound of the invention (0.3 gm) in 90%yield.

Analysis:

MS (ES−) C₉H₁₁N₄O₆SNa=303.3 (M−1) as a free sulfonic acid;

H¹NMR (DMSO-d₆)=4.59 (d, 1H), 4.04 (br s, 1H), 2.92 (br d, 1H), 2.73 (d,1H), 2.5 (s, 3H), 2.10-2.16 (m, 1H), 1.92-2.02 (m, 2H), 1.80-1.88 (m,1H).

Compounds 2 to 12 (Table 1) were prepared using the procedure describedas in Example-1 and using corresponding R₁CONHNH₂, in the place ofacetic acid hydrazide.

TABLE 1 Exam- ple Acid hydrazide Mass (ES-1) No. (R₁CONHNH₂) R₁ H¹ NMR(DMSO-d₆) as free acid (MF)  2. C₂H₅—CONHNH₂ —C₂H₅ 4.59 (d, 1H), 4.03(br s, 1H), 2.93 (br, d 1H), 2.84 (q, 317.1 2H), 2.59 (d, 1H), 2.06-2.16(m, 1H), 1.94-2.02 (m, (C₁₀H₁₃N₄O₆S•Na) 2H), 1.83-1.88 (m, 1H), 1.25 (q,3H).  3. CF₃—CONHNH₂ —CF₃ 4.73, (d, 1H), 4.06 (br s, 1H), 2.93 (br d,1H), 3.00 (d, 357.2 1H), 2.12-2.25 (m, 1H), 1.95-2.12 (m, 2H), 1.80-1.90(C₉H₈F₃N₄O₆S•Na) (m, 1H).  4. NH₂CO—CONHNH₂ NH₂CO— 8.62 (s, 1H), 8.20(s, 1H), 4.70 (d, 1H), 4.05 (br s, 1H), 332.3 2.94 (br d, 1H), 2.79 (d,1H), 2.18-2.24 (m, 1H), 1.98- (C₉H₁₀N₅O₇S•Na) 2.10 (m, 2H), 1.81-1.90(m, 1H).  5.

9.30 (d, 1H), 7.30 (d, 1H), 4.76 (d, 1H), 4.06 (br s, 1H), 2.98 (br d,1H), 2.85 (d, 1H), 2.10-2.28 (m, 1H), 1.98- 2.10 (m, 2H), 1.82-1.95 (m,1H). 356.2 (C₁₁H₁₀N₅O₇S•Na)  6.

8.05 (d, 1H), 7.40 (d, 1H), 6.78 (s, 1H), 4.70 (d, 1H), 4.05 (br s, 1H),2.96 (br d, 1H), 2.81 (d, 1H), 2.19-2.30 (m, 1H), 1.80-2.10 (m, 2H),1.84-1.95 (m, 1H). 355.2 (C₁₂H₁₁N₄O₇S•Na)  7.

8.01 (d, 1H), 7.58-7.65 (m, 1H), 4.72 (d, 1H), 4.07 (br s, 1H), 2.98 (brd, 1H), 2.85 (d, 1H), 2.20-2.27 (m, 1H), 1.96-2.08 (m, 2H), 1.87-1.94(m, 1H). 365.2 (C₁₄H₁₃N₄O₆S•Na)  8.

8.78 (d, 1H), 8.19 (d, 1H), 8.031-8.07 (m, 1H), 7.62- 7.65 (m, 1H), 4.76(d, 1H), 4.07 (br s, 1H), 3.00 (br d, 1H), 2.83 (d, 1H), 2.20-2.30 (m,1H), 2.00-2.11 (m, 2H), 1.87-1.94 (m, 1H). 366.2 (C₁₃H₁₂N₅O₆S•Na)  9.

8.35-8.37 (m, 1H), 8.20-8.23 (m, 2H), 8.01 (br s, 1H), 7.85 (br s, 1H),4.78 (d, 1H), 4.08 (br s, 1H), 3.99 (br d, 1H), 2.90 (d, 1H), 2.25-2.31(m, 1H), 2.02-2.12 (m, 2H), 1.93-1.97 (m, 1H). 409.2 (C₉H₁₁N₄O₆S•Na) 10.

8.03 (s, 1H), 4.78 (s, 2H), 4.68 (d, 1H), 4.10-4.12 (m, 2H), 4.01-4.05(m, 3H), 2.97 (br d, 1H), 2.75 (d, 1H), 2.10-2.20 (m, 1H), 1.99-2.07 (m,2H), 1.89-1.96 (m, 1H). 411.2 (C₁₄H₁₅N₆O₇S•Na) 11.

4.64 (d, 1H), 4.04 (br s, 1H), 3.76-3.86 (m, 2H), 3.56 (t, 4H), 2.94 (brd, 1H), 2.69 (d, 1H), 2.44-2.48 (m, 4H), 2.12-2.22 (m, 1H), 1.93-2.06(m, 2H), 1.60-1.80 (m, 1H). 388.2 (C₁₃H₁₈N₅O₇S•Na) 12.

4.71 (d, 1H), 4.06 (br s, 1H), 3.92-3.96 (m, 2H), 3.60- 3.69 (m, 6H),2.98 (br d, 1H), 2.78 (d, 1H), 2.18-2.22 (m, 1H), 1.95-2.05 (m, 2H),1.80-1.90 (m, 1H). 402.0 (C₁₃H₁₆N₅O₈S•Na)

Example-13 trans-sulfuric acidmono-[2-(5-aminomethyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester

Tetrabutylammonium salt of trans-sulfuric acidmono-[2-(5-aminomethyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester(600 mg, obtained by following procedure from Step-1 to Step-4 asdescribed in Example-1 and by using tert-butoxycarbonylamino acetic acidhydrazide in the place of acetic acid hydrazide) was added, a solutionof trifluoroacetic acid (1.2 ml) in dichloromethane (1.2 ml) slowly bysyringe at −5° C. over a period of 5 minutes. The mixture was maintainedunder stirring for 1 hour. Solvents were removed below 40° C. under highvacuum to provide a residue which was triturated with diethyl ether (50ml×5) and each time diethyl ether was decanted. The obtained white solidwas further triturated with acetonitrile (50 ml×2). The resultant solidwas stirred in dichloromethane (50 ml) and the suspension was filtered.The solid was dried under vacuum to provide title compound of inventionin 0.265 gm quantity.

Analysis:

MS (ES−) C₉H₁₃N₅O₆S.CF₃COOH=318.2 (M−1) as a free sulfonic acid;

H¹NMR (DMSO-d₆ after D2O exchange)=4.69 (d, 1H), 4.45 (s, 2H), 4.09 (brs, 1H), 2.97 (br d, 1H), 2.74 (d, 1H), 2.17-2.19 (m, 1H), 1.94-2.10 (m,2H), 1.80-2.00 (m, 1H).

Compounds 14 to 19 (Table 2) were prepared using a procedure describedin Example-13 and using corresponding R₁CONHNH₂, wherein the aminefunction is protected with BOC group.

TABLE 2 Example Acid hydrazide Mass (ES-1) No. (R₁CONHNH₂) R₁ H¹ NMR(DMSO-d₆) as free acid (MF) 14.

8.64, (br s, 3H), 4.87 (q, 1H), 4.69 (d, 1H), 4.09 (br s, 1H), 2.98 (brd, 1H), 2.75 (d, 1H), 2.16-2.21 (m, 1H), 2.00-2.21 (m, 2H), 1.82-1.90(m, 1H), 1.58 (d, 3H). 332.3 (C₁₀H₁₅N₅O₆S) 15.

8.65 (br s, 3H), 4.87 (q, 1H), 4.69 (d, 1H), 4.09 (br s, 1H), 2.98 (brd, 1H), 2.73 (d, 1H), 2.16-2.21 (m, 1H), 1.99-2.09 (m, 2H), 1.82-1.90(m, 1H), 1.58 (d, 3H). 332.2 (C₁₀H₁₅N₅O₆S) 16.

8.50 (br s, 1H), 8.32 (br s, 1H), 4.61 (d, 1H), 4.05 (br s, 1H),3.26-3.29 (m, 2H), 3.04 (t, 2H), 2.93- 3.02 (br d, 1H), 2.72 (d, 1H),2.13-2.20 (m, 3H), 1.82-2.02 (m, 6H). 372.2 (C₁₃H₁₈N₅O₆S) 17.

9.48 (br s, 2H), 5.04 (t, 1H), 4.67 (d, 1H), 4.09 (br s, 1H), 3.30-3.39(m, 2H), 2.98 (br d, 1H), 2.81 (d, 1H), 2.38-2.46 (m, 1H), 2.22-2.34 (m,1H), 2.17-2.20 (m, 1H), 1.98-2.10 (m, 4H), 1.80-1.89 (m, 1H). 358.3(C₁₂H₁₇N₅O₆S) 18.

8.45 (br s, 2H), 4.63 (d, 1H), 4.06 (br s, 1H), 3.91- 3.99 (m, 2H), 3.10(br s, 4H), 2.96 (br d, 1H), 2.65- 2.73 (m, 5H), 2.05-2.20 (m, 1H),1.94-2.05 (m, 2H), 1.80-1.88 (m, 1H). 387.2 (C₁₃H₂₀N₆O₆S) 19.

9.31 (br s, 2H), 7.43-7.55 (m, 6H), 6.19 (s, 1H), 4.69 (dd, 1H), 4.07(br s, 1H), 2.91-3.00 (m, 2H), 2.64-2.70 (m, 1H), 2.12-2.20 (m, 1H),1.94-2.04 (m, 2H), 1.80-1.90 (m, 1H). 393.9 (C₁₅H₁₇N₅O₆S)

Example-20 Sodium salt oftrans-6-(sulphooxy)-2-(5-methyl-[1,3,4]-thiadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

Step-1: Preparation oftrans-2-(N″-acetylhydrazinocarbonyl)-5-benzyloxyamino-piperidine-1-carboxylicacid-tert-butyl ester

To a solution of trans-5-benzyloxyamino-piperidine-1,2-dicarboxylicacid-1-tert-butyl ester (12 gm, 0.034 mol) in N,N-dimethyl formamide (60ml), EDC-HCl (9.82 gm, 0.051 mol) and N-methyl morpholine (11.4 ml) wereadded successively at 10° C. to 15° C. under stirring. To the reactionmixture, were added acetyl hydrazide (2.79 gm, 0.0377 mol) and HOBt(4.62 gm, 0.034 mol). The resulting mixture was allowed to warm at 25°C. to 35° C. and stirred for 16 hours. The reaction mixture was pouredinto water (600 ml) and stirred for 30 min. The separated solid wasfiltered and the filtrate was extracted with ethyl acetate (3×400 ml).The combined organic extract was dried over sodium sulphate and thesolvent was evaporated under vacuum to provide a residue. The residuewas purified by column chromatography to obtain the Step-1 product, as apale yellow thick oil in 9.8 gm quantity (yield 70%).

Analysis:

MS: 407 (M+H); MF: C₂₀H₃₀N₄O₅; MW: 406.49.

Step-2: Preparation oftrans-2-(5-methyl-[1,3,4]-thiadiazol-2-yl)-5-benzyloxyamino-piperidine-1-carboxylicacid-tert-butyl ester

To a solution of step-1 product (9.6 gm, 0.0236 mol) in toluene (240 ml)was added Lawesson's reagent (12.4 gm, 0.0307 mol) and the resultingmixture heated to 60° C. to 65° C. for 2 hours under stirring. Thereaction mixture was allowed to cool to 25° C. to 35° C. and washed withsaturated sodium bicarbonate solution (2×150 ml). The organic layer wasseparated, dried and the solvent was evaporated under vacuum to providea residue. The residue was purified by column chromatography to obtainstep-2 product as pale yellow oil, in 9.5 gm quantity.

Analysis:

MS: 405 (M+H); MF: C₂₀H₂₈N₄O₃S; MW: 404.54;

Step-3: Preparation oftrans-2-(5-methyl-[1,3,4]-thiadiazol-2-yl)-5-benzyloxyamino-piperidine

To a solution of Step-2 product (9.5 gm, 0.0236 mol) in dichloromethane(19 ml) was added trifluoro acetic acid (38 ml) at 10-15° C., over aperiod of 5 min, under stirring. The resulting solution was allowed tostir at 25° C. to 35° C. for 30 min. and the solution was concentratedunder vacuum to provide a residue. The residue was diluted with water(50 ml) and aqueous sodium bicarbonate solution. It was extracted withethyl acetate (2×100 ml). The combined organic layer was dried oversodium sulphate and was evaporated under vacuum to provide a residue.The residue was purified by column chromatography to obtain step-3product, as off-white solid, in 4.4 gm quantity (yield 62%)

Analysis:

MS: 305 (M+H); MF: C₁₅H₂₀N₄OS; MW: 305.

Step-4: Preparation oftrans-2-(5-methyl-[1,3,4]-thiadiazol-2-yl)-6-benzyloxy-7-oxo-1,6-diazabicyclo[3.2.1]-octane

To a solution of Step-3 product (4.4 gm, 0.0144 mol) and triethylamine(6.02 ml, 0.0432 mol) in acetonitrile (66 ml) was added a solution oftriphosgene (2.57 gm, 0.00865 mol) in acetonitrile (22 ml) at 10° C. to15° C. over a period of 10 minutes under stirring. N,N dimethylaminopyridine (176 mg, 0.00144 mol) was added to the reaction mixture after30 min. and the mixture was then allowed to warm to 25° C. to 35° C. andstirred for 16 hours. The resulting mixture was quenched with saturatedsodium bicarbonate solution (30 ml). The solvents were evaporated undervacuum to provide a residue. The residue was purified by columnchromatography to obtain the Step-4 product as off-white solid in 1.1 gmquantity (yield 23%).

Analysis:

MS: 331 (M+H); MF: C₁₆H₁₈N₄O₂S; MW: 330.

Step-5: Preparation oftrans-2-(5-methyl-[1,3,4]-thiadiazol-2-yl)-6-hydroxy-7-oxo-1,6-diazabicyclo[3.2.1]-octane

To a solution of Step-4 product (1.1 gm, 0.0033 mol) in methanol (100ml), was added ammonium formate (10 gm) followed by 10% Pd/C (2.2 gm, 2times w/w). The suspension was stirred for 4 hrs at 25° C. to 35° C. Thecatalyst was filtered thorough celite, and the filtrate was concentratedunder vacuum to obtain Step-5 product in 0.7 gm quantity (yield 90%),which was used as such for the next reaction.

Analysis:

MS: 241 (M+H); MF: C₉H₁₂N₄O₂S; MW: 240

Step-6: Preparation of tetrabutylammonium salt oftrans-6-(sulphooxy)-2-(5-methyl-[1,3,4]-thiadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

To a solution of Step-5 product (630 mg) in a mixture of N,N-dimethylformamide: dichloromethane (3 ml: 3 ml) was added N,N-dimethyl formamidesulfur trioxide complex (480 mg) at 0° C. to 5° C. under stirring. Thereaction mixture was stirred for 30 min. It was concentrated undervacuum to remove dichloromethane and to the leftover solution, was addeda solution of tetrabutyl ammonium acetate (956 mg) in water (3 ml). Thereaction mixture was stirred for 16 hours at 25° C. to 35° C. It wasconcentrated under reduced pressure (4 mm Hg) to provide a residue. Tothe residue, water (10 ml) was added and the mixture was extracted withdichloromethane (2×15 ml). The combined organic layer was concentratedunder vacuum to obtain the step-6 product as a white solid in 590 mgquantity (yield 54%).

Analysis:

MS: 562 (M+H); MF: C₂₅H₄₇N₅O₅S₂; MW: 561

Step-7: Sodium salt oftrans-6-(sulphooxy)-2-(5-methyl-[1,3,4]-thiadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

The product obtained as in Step-6 was dissolved in 20% tetrahydrofuranin water (1 ml) and the above solution was passed through a column ofAmberlite SR01-L-Na resin (15 g). The column was first eluted withTHF-water (10:1, 50 ml) followed by water (50 ml). The combined aqueouslayer fractions were evaporated under vacuum to obtain the compound ofinvention as off-white solid in 250 mg quantity (Yield 70%).

Analysis:

MS: 319 (M−H of free sulphonic acid); MF: C₉H₁₁N₄O₅S₂Na; MW: 342.33

H¹NMR (D₂O)=4.85 (d, 1H), 4.122 (br s, 1H), 3.11 (br d, 1H), 2.88 (d,1H), 2.66 (s, 3H), 2.42-2.37 (m, 1H), 2.16-2.05 (m, 2H), 1.89-1.82 (m,1H).

Example-21 Sodium salt oftrans-6-(sulphooxy)-2-(5-methyl-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

Step-1: Preparation oftrans-5-benzyloxyamino-2-carboxamido-piperidine-1-carboxylicacid-1-tert-butyl ester

To a stirred solution oftrans-5-benzyloxyamino-piperidine-1,2-dicarboxylic acid-1-tert-butylester (21 gm, 0.06 moles) and triethylamine (25.12 ml, 0.18 moles) indichloromethane (210 ml) was added pivaloyl chloride (11.07 ml, 0.09moles) dropwise at a temperature of 0° C. The resulting mixture wasstirred for 1.5 hours. The reaction mixture was cooled to −40° C. anddry ammonia gas was bubbled for 30 min. It was allowed to warm to 25° C.to 35° C. and the resulting suspension was filtered off. The filtratewas evaporated under reduced pressure to provide a residue, and theresidue was chromatographed on a column of silica gel to provide thestep-1 product, as thick oil, in 10.2 gm quantity, (yield: 49%).

Analysis:

MS: 348[M⁺]; MF: C₁₉H₂₈N₂O₄; MW: 348.

Step-2: Preparation oftrans-5-benzyloxyamino-2-cyano-piperidine-1-carboxylic acid-1-tert-butylester

To a solution of Step-1 compound (10.2 gm, 0.0286 moles) andtriethylamine (17.99 ml, 1.289 moles) in dichloromethane (306 ml) wasadded of trifluoro acetic anhydride (12.08 gm, 0.0573 moles) at 0° C.under stirring. The resulting solution was allowed to warm to 25° C. to35° C. and stirred for 6 hours. The reaction mixture was washedsuccessively by water (3×100 ml), saturated aqueous ammonium chloridesolution (100 ml) and brine (100 ml). The combined organic layer wasdried over sodium sulfate and the solvent was evaporated under vacuum toprovide a residue. The residue was chromatographed on a column of silicagel using a mixture of acetone:hexane (1:19), to provide the step-2product, as a white solid, in 9.7 gm quantity (yield-quantitative).

Analysis:

MS: 331 (M⁺); MF: C₁₈H₂₅N₃O₃; MW: 331.

Step-3: Preparation oftrans-5-benzyloxyamino-2-(N-hydroxy-carbamimidioyl)-piperidine-1-carboxylicacid-1-tert-butyl ester

To a cooled solution of step-2 product (9.7 gm, 0.0293 moles) inmethanol (145.5 ml) was added successively, hydroxylamine hydrochloride(3.05 gm, 0.0439 moles) and sodium bicarbonate (5.53 gm, 0.0659 moles)at 0° C. under stirring. The reaction mixture was allowed to warm to 25°C. to 35° C. and stirred for 24 hrs. The resulting suspension wasfiltered off and the filtrate was concentrated under vacuum below 40° C.to provide a residue. The residue was purified by column chromatographyover silica-gel with a mixture of acetone:hexane (1:5) to provide thestep-3 product, as colorless oil, in 7.6 gm quantity (yield: 72%).

Analysis:

MS: 364 (M+); MF: C₁₈H₂₈N₄O₄; MW: 364.

Step-4: Preparation oftrans-5-benzyloxyamino-2-(N-acetyloxy-carbamimidioyl)-piperidine-1-carboxylicacid-1-tert-butyl ester

To a solution of Step-3 product (7.6 gm, 0.0208 moles) indichloromethane (76 ml) was added triethylamine (5.82 ml, 0.0417 moles)followed by acetic anhydride (2.34 gm, 0.02293 moles) dropwise at 0° C.The resulting mixture was allowed to warm to 25° C. to 35° C. andstirred for 4 hours. The reaction mixture was washed successively, withwater (2×75 ml), saturated aqueous ammonium chloride solution (75 ml),and brine (35 ml). The organic layer was dried over sodium sulfate andevaporated under vacuum to provide a residue. The residue waschromatographed on a column of silica gel with 1:10 mixture of acetone:hexane to yield Step-4 product as white solid, in 7.5 gm quantity(yield: 88%).

Analysis:

MS: 405 (M+); MF: C₂₁H₃₁N₃O₅; MW: 405.

Step-5: Preparation oftrans-5-benzyloxyamino-2-(5-methyl-[1,2,4]-oxadiazol-3-yl)-piperidine-1-carboxylicacid-1-tert-butyl ester

A solution of Step-4 product (7.5 gm) in pyridine (112.5 ml) was heatedat reflux temperature for 6 hours. The solvent was evaporated undervacuum below 40° C., and the residue was diluted with 10% aqueous KHSO₄solution (100 ml). The mixture was extracted with ethyl acetate (3×75ml). The combined organic extracts were washed with water (2×75 ml)followed by brine (37.5 ml). Organic layer was dried over sodium sulfateand the solvent was evaporated under vacuum to provide a residue. Theresidue was purified by column chromatography with 1: 20 mixture ofacetone: hexane, to afford the step-5 product as a white solid, in 6.0gm quantity (yield: 84) %.

Analysis:

MS: 387 (M+); MF: C₂₁H₂₉N₃O₄; MW: 387.

Step-6: Preparation oftrans-6-benzyloxyamino-2-(5-methyl-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diaza-bicyclo[3.2.1]-octane

To a solution of Step-5 product (6 gm) in dichloromethane (150 ml) wasadded trifluoro acetic acid (12 ml) at −15° C. under stirring and theresulting mixture was allowed to warm to 25° C. to 35° C. It was stirredfor 4 hours. The solvent was evaporated under vacuum below 40° C. Theresulting mass was diluted with saturated aqueous sodium bicarbonatesolution (60 ml) and the mixture was extracted with dichloromethane(2×60 ml). The combined organic extracts were washed with water (60 ml),dried over sodium sulphate and evaporated under vacuum below 40° C. toobtain 4.2 gm of tert-butoxycarbonyl group deprotected piperidinecompound.

To the solution of tert-butoxycarbonyl group deprotected piperidinecompound (4.2 gm) in acetonitrile (63 ml) was added triethyl amine (5.28ml) followed by a solution of triphosgene (1.9 gm) in acetonitrile (16.8ml) at 0° C. to 5° C. under stirring. It was stirred for 30 min. andN,N-dimethyl amino pyridine (0.178 gm) was added. The reaction mixturewas allowed to warm to 25° C. to 35° C. and stirred for 16 hours. To thereaction mixture saturated aqueous solution of sodium bicarbonate (33.6ml) was added and the resulting mixture was stirred for 30 min. Themixture was concentrated to its ⅓^(rd) volume under vacuum and it wasdiluted with water (42 ml) and the resulting mixture extracted withdichloromethane (2×40 ml). The combined organic layer was evaporatedunder vacuum to provide a residue and the residue purified over a columnof silica gel using 1:4 mixture of acetone: hexane to provide the step-6product as white solid, in 2.3 g quantity (yield: 48%).

Analysis:

MS: 314 (M+); MF; C₁₆H₁₈N₄O₃; MW; 314.

Step-7: Preparation of tetrabutylamoonium salt oftrans-6-sulfooxy-2-(5-methyl-1,2,4′-oxadiazol-3-yl)-7-oxo-1,6-diaza-bicyclo[3.2.1]-octane

A solution of Step-6 product (2.3 gm, 0.00732 mole) in a mixture ofdichloromethane and N,N-dimethylformamide (11.5 ml each) was added 10%palladium on carbon (575 mg) and the suspension was stirred underhydrogen atmosphere (1 atm) at 25° C. to 35° C. for 5 hours. Thecatalyst was filtered and the filtrate was concentrated under reducedpressure to obtain the debenzylated product. This was used as such forthe next reaction. The debenzylated product obtained as above, wasdissolved in N,N-dimethylformamide (11.5 ml), and to the clear solutionwas added in one portion N,N-dimethyl formamide sulfur trioxide complex(1.34 gm, 0.00878 mole) under argon atmosphere, at 0° C. The reactionmixture was stirred for 1 hour. Tetra butyl ammonium sulfate (2.66 gm,0.0.00878 mole) dissolved in water (8.8 ml) was added to the reactionmixture and the resulting mixture was allowed to warm to 25° C. to 35°C. and stirred for 1 hour. The solvents were removed under vacuum below40° C. to provide a residue and it was triturated with xylene (25 ml) toremove traces of N,N′-dimethylformamide. The residue was partitionedbetween a 1:1 mixture of water (23 ml) and dichloromethane (23 ml) andlayers were separated. The aqueous layer was re-extracted withdichloromethane (23 ml). The combined organic extracts were washedsuccessively with water (23 ml) and brine (23 ml). The organic layer wasdried over sodium sulfate and concentrated under vacuum to obtain thestep-7 product in 2.05 gm quantity (yield-51%).

Analysis:

MS: 304 (M−H) of sulfate; M.F: C₂₅H₄₇N₅O₆S; M.W: 545.7.

Step-8: Sodium salt oftrans-6-sulfooxy-2-(5-methyl-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diaza-bicyclo[3.2.1]-octane

The Step-7 product (1.7 g) was dissolved in 5% tetrahydrofuran in watermixture (2 ml), and the solution was loaded on a column of Dowex 50WX8200 Na⁺ resin (25 cm×3.0 cms). The column was eluted with 5%tetrahydrofuran in water (50 ml) followed by water (150 ml). Evaporationof the fractions under vacuum below 40° C. provided the title compoundof the invention, as a white solid, in 860 mg quantity (yield 85%).

Analysis:

MS: 304 (M−H) of sulfate; M.F: C₉H₁₁N₄NaO₆S; M.W: 326.27.

H¹NMR (DMSO-d₆ after D₂O exchange)=4.46 (t, 1H), 4.02 (br s, 1H), 2.90(br s, 2H), 2.59 (s, 3H), 2.06-1.93 (m, 3H), 1.83-1.77 (m, 1H).

Example-22 Sodium salt oftrans-6-(sulphooxy)-2-(5-ethoxycarbonyl-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

By following the procedure described in Example-21 and using ethyl esterof oxalyl chloride in the place of acetic anhydride in Step-4, the titlecompound was obtained in 731 mg quantity.

Analysis:

MS: 333 (M−H) of sulfate; M.F: C₉H₁₀N₅NaO₇S; M.W: 355.

H¹NMR (DMSO-d₆ after D₂O exchange)=4.61 (d, 1H), 4.41 (q, 2H), 4.04 (brs, 1H), 2.92-2.82 (m, 2H), 2.09-2.03 (m, 2H), 1.99-1.96 (m, 1H),1.83-1.81 (m, 1H), 1.33 (t, 3H).

Example-23 Sodium salt oftrans-6-(sulphooxy)-2-(2-methyl-2H-[1,2,3,4]-tetrazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

Step-1: Preparation oftrans-5-benzyloxyamino-2-(1H-tetrazol-5-yl)-piperidine-1-carboxylicacid-1-tert-butyl ester

To a solution of trans-5-benzyloxyamino-2-cyano-piperidine-1-carboxylicacid-1-tert-butyl ester (6 gm, 0.018 mol) in toluene (120 ml) were addedsodium azide (5.88 gm, 0.090 mol), triethylamine hydrochloride (12.42gm, 0.090 mol) and the resulting mixture was heated to 100° C., understirring for 2 hours. The reaction mixture was cooled to 25° C. to 35°C. and poured into saturated aqueous ammonium chloride solution (150ml). The mixture was stirred for 15 min. and aqueous layer was extractedwith ethyl acetate (1×120 ml). The combined organic layer was dried oversodium sulfate and was concentrated under vacuum to obtain the step-1product as colorless oil, in 6.0 gm quantity (yield 89%).

Analysis:

MS: 375 (M−H); FW: C₁₈H₂₆N₆O₃; MW: 376.

Step-2: Preparation of isomers: isomer Atrans-5-benzyloxyamino-2-(1-methyl-1H-tetrazol-5-yl)-piperidine-1-carboxylicacid-1-tert-butyl ester and isomer Btrans-5-benzyloxyamino-2-(2-methyl-2H-tetrazol-5-yl)-piperidine-1-carboxylicacid-1-tert-butyl ester

To a mixture of step-1 product (6.0 gm, 0.0168 mol) and cesium carbonate(7.84 gm, 0.0240 mol) in N,N-dimethylformaide (60 ml) was added methyliodide (3.41 gm, 0.0240 mol) at a temperature of 0° C. to 5° C., understirring. The reaction mixture was stirred for 30 min, warmed to 25° C.to 35° C. and stirred for 2 hours. It was poured onto ice water (600 ml)and extracted with ethyl acetate (3×150 ml). The combined organic layerwas dried over sodium sulfate and concentrated under vacuum to provide aresidue. The residue was purified by column chromatography usingmixtures of 5-20% ethyl acetate in hexane to obtain two isomers Isomer Aat Rf 0.50 and Isomer B: at Rf 0.42. These isomers were individuallyidentified. Total quantity of products obtained was 5.7 gm (yield 91%).

Analysis:

MS: 389 (M−H); FW: C₁₉H₂₈N₆O₃; MW: 390

Step-3: Preparation oftrans-5-benzyloxyamino-2-(2-methyl-2H-tetrazol-5-yl)-piperidine-1-carboxylicacid

To a solution of isomer B as obtained in Step-2 (1.35 gm, 0.00347 mol)in dichloromethane (13.5 ml) was added trifluoro acetic acid (2.7 ml) at0° C., under stirring. It was allowed to warm to 25° C. to 35° C. andstirred for 4 hours. The reaction mixture was concentrated under vacuumto provide a residue and the residue was diluted with water (20 ml) andtreated with saturated aqueous sodium bicarbonate solution (5 ml). Theresulting mixture was extracted with dichloromethane (2×20 ml). Thecombined extracts were dried over sodium sulfate and concentrated undervacuum to obtain the step-3 product as colorless oil, in 900 mg quantity(yield 90%).

Analysis:

MS: 288 (M+); FW: C₁₄H₂₀N₆O; MW: 288.

Step-4: Preparation oftrans-6-(benzyloxy)-2-(2-methyl-2H-1,2,3,4′-tetrazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

To a solution of Step-3 product (900 mg, 0.00321 mol) and triethylamine(1.3 ml, 0.00937 mol) in acetonitrile (13.5 ml) was added a solution oftriphosgene (400 mg, 0.00137 mol) in acetonitrile (3.6 ml) at 0° C.under stirring. To the mixture was added N,N-dimethylamino pyridine (38mg, 0.00031 mol) after 30 minutes and the reaction mixture was allowedto warm to 25° C. to 35° C. It was stirred for 16 hours. The reactionmixture was diluted with saturated aqueous sodium bicarbonate solution(9 ml) and the organic solvent was evaporated under reduced pressure toprovide a mass. The mass was extracted with dichloromethane (2×10 ml).The combined organic layer was concentrated under vacuum to provide aresidue and the residue was purified by column chromatography usingmixtures of 15-20% ethyl acetate in hexane to provide the Step-4 productas colorless oil, in 300 mg quantity (yield 32%).

Analysis:

MS: 315 (M+H): FW: C₁₅H₁₈N₆O₂; MW: 314.35.

Step-5: Preparation oftrans-6-(hydroxy)-2-(2-methyl-2H-1,2,3,4′-tetrazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

To a solution of Step-4 product (300 mg, 0.00095 mol) in a mixture ofethyl acetate: methanol (3 ml: 0.6 ml), was added 10% Pd/C (60 mg, 2times w/w) and the mixture stirred under hydrogen atmosphere at 25° C.to 35° C. for 2 hours. The catalyst was filtered thorough celite and thefiltrate was evaporated under vacuum to obtain the Step-5 product ascolorless oil, in 200 mg quantity (yield 93%). This was used as such forthe next reaction.

Analysis:

MS: 224 (M+); FW: C₈H₁₂N₆O₂, MW: 224.

Step-6: Preparation of tetrabutylammonium salt oftrans-6-(sulphooxy)-2-(2-methyl-2H-[1,2,3,4]-tetrazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

To a solution of Step-5 product (200 mg) in N,N-dimethyl formamide (1ml) was added N,N-dimethyl formamide sulfur trioxide complex (488 mg) inone lot at 0° C. under stirring. The resulting mixture was allowed towarm at 25° C. to 35° C. and stirred for 2 hours. A solution oftetrabutylammonium acetate (636 mg) in water (2.1 ml) was added to thereaction mixture. The mixture was stirred further for 16 hours. Thesolvent was evaporated under vacuum below 40° C. temperature to providea residue, and the residue was diluted with water (10 ml). The resultingmixture was extracted with dichloromethane (2×10 ml). The combinedorganic layer was concentrated under vacuum to obtain the Step-6 productas white solid, in 275 mg quantity (yield 51%).

Analysis:

MS: 599 (M+H); FW: C₂₅H₄₉N₇O₅S; MW: 599.

Step-7: Sodium salt oftrans-6-(sulphooxy)-2-(2-methyl-2H-[1,2,3,4]-tetrazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

The Step-6 product (270 mg) was dissolved in 20% tetrahydrofuran inwater (2 ml) and the resulting solution was loaded on activated Dowex 50WX8-200-Na column (45 cm length×3 cm diameter). The column was elutedwith tetrahydrofuran (100 ml) followed by 50% tetrahydrofuran watermixture. The product containing fractions were evaporated under vacuumbelow 40° C. to obtain the title compound of invention, as a whitehygroscopic solid, in 100 mg quantity (yield 67%).

Analysis:

MS: 303 (M−H as a free sulphonic acid); FW for C₈H₁₁N₆NaO₅S; MW: 326.27.

H¹NMR (DMSO-d₆ after D₂O exchange)=4.64 (t, 1H), 4.36 (s, 3H), 4.03 (brs, 3H), 2.85 (br s, 2H), 2.07-2.04 (m, 2H), 2.00 (m, 1H), 1.91-1.85 (m,1H).

Example-24 Sodium salt oftrans-6-(sulphooxy)-2-(1-methyl-1H-[1,2,3,4]-tetrazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

The title compound of invention was prepared by using isomer A obtainedin Step-2 of Example-23 and by using the procedure described inExample-23 and using isomer obtained in Step-3.

Analysis:

H¹NMR (DMSO-d₆ after D₂O exchange)=4.82 (d, 1H), 4.04 (s, 3H), 2.83 (brd, 1H), 2.50 (d, 1H), 2.22-2.18 (m, 1H), 2.08-2.03 (m, 1H), 2.00-1.96(m, 2H).

Example-25 Sodium salt oftrans-6-sulphooxy-2-(3-ethoxycarbonyl-[1,2,4]-oxadiazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

Step-1: Preparation oftrans-6-benzyloxy-2-(ethoxycarbonylformamindino-N-oxy-carbonyl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

To a solution oftrans-6-benzyloxy-7-oxo-1,6-diazabicyclo[3.2.1]-octane-2-carboxylic acid(2.5 gm, 9.05 mmol) in N,N-dimethylformamide (25 ml) was added EDChydrochloride (2.56 g, 13.58 mmol), HOBt (1.22 g, 9.05 mmol),N-hydroxy-ethoxycarbonylformamidine (669 mg, 9.05 mmol) and N-methylmorpholine (3 ml, 27.15 mmol) successively at a temperature between 10°C. to 15° C., under stirring. The reaction mixture was allowed to warmat 25° C. to 35° C. temperature and stirred for 24 hours. It was pouredinto water (250 mL) to provide a suspension. The suspension was filteredand the filtrate was extracted with ethyl acetate (3×100 mL). Thecombined organic extracts were dried over sodium sulfate and evaporatedunder vacuum to provide a residue. The residue was purified by columnchromatography, using ethyl acetate, hexane (5:5) to obtain the Step-1product, as a white solid, in 1.5 gm quantity (yield 42%).

Analysis:

MS: 391 (M+H); MW: 390; M.F: C₁₈H₂₂N₄O₆

Step-2: Preparation oftrans-6-benzyloxy-2-(3-ethoxycarbonyl-[1,2,4]-oxadiazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

A solution of Step-1 product (1.5 gm) in pyridine (15 ml) was heated to110° C. to 115° C. under argon atmosphere for 2.5 hours. The solvent wasevaporated under vacuum to provide a residue. The residue was purifiedby column chromatography, using ethyl acetate, hexane (5:5) to providestep-2 product, as white solid, in 1 gm quantity (yield 70%).

Analysis:

MS: 373.2 (M+H); M.W: 372; M.F.: C₁₈H₂₀N₄O₅.

Step-3: Preparation of tetrabutylammonium salt oftrans-6-sulphooxy-2-(3-ethoxycarbonyl-[1,2,4]-oxadiazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

To a solution of Step-2 product (100 mg, 0.268 mmol) in a mixture ofdichloromethane and N,N′-dimethylformamide (250 μL each) was added 10%palladium on carbon (25 mg) and the resulting mixture was stirred underhydrogen atmosphere for 1 hour at 25° C. to 35° C. The catalyst wasfiltered through micron filter and the filtrate was concentrated undervacuum below 40° C. to provide a residue. The residue was dissolved inN,N-dimethylformamide (500 μL) and N,N-dimethylformamide sulfurtrioxidecomplex (50 mg, 0.321 mmol) was added in one lot at 0° C. temperature.The mixture was stirred for 1 hour. The aqueous tetrabutyl ammoniumacetate solution (97 mg, 0.321 mmol dissolved in 350 μL water) was thenadded to it. The reaction mixture was allowed to warm to 25° C. to 35°C. and stirred further for 1 hour. The volatiles were removed undervacuum to provide a residue and residue was triturated with xylene (10ml) to remove traces of N,N-dimethylformamide. Residue was partitionedbetween water (10 ml) and dichloromethane (10 ml). Aqueous layer wasre-extracted with dichloromethane (10 ml). Combined organic extractswere washed with water (10 ml) and brine (10 ml). Organic layer wasdried over sodium sulfate and concentrated under vacuum to obtain yellowoil as the Step-3 product, in 100 mg quantity (yield 62%).

Analysis:

MS: 361.2 (M−H) of free sulfonic acid; M.W: 603: M.F:C₁₁H₁₃N₄O₈S:C₁₆H₃₆N.

Step-4: Sodium salt oftrans-6-sulphooxy-2-(3-ethoxycarbonyl-[1,2,4]-oxadiazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

The Step-3 product (100 mg) was dissolved in 50% aqueous tetrahydrofuranand the solution was loaded over Amberlite 200 Na⁺ resin column (20 cmlength, 3 cm diameter). The column was eluted with 50% aqueoustetrahydrofuran. The desired fractions were evaporated under vacuumbelow 40° C. to provide title compound of the innovation as a whitesolid, in 30 mg quantity (yield 47%).

Analysis:

MP: 184-189 (Dec);

MS: 361.2 (M−H) as a free sulfonic acid; M.F: C₁₁H₁₃N₄O₈S Na.

H¹NMR (DMSO-d₆ after D₂O exchange)=4.81 (d, 1H), 4.42 (q, 2H), 4.03 (brs, 1H), 3.02 (br d, 1H), 2.79 (d, 1H), 2.22-2.16 (m, 1H), 2.09-1.96 (m,2H), 1.85-1.82 (m, 1H), 1.32 (t, 3H).

Example-26trans-6-(sulphooxy)-2-(5-(piperidin-4-yl-)-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

By following the procedure described in Example-21 and usingpiperidine-4-carboxylic acid chloride in the place of acetic anhydridein Step-4, the title compound was obtained in 52 mg quantity.

Analysis:

MS: 373.1 (M−H) of sulfate; M.F: C₁₃H₁₉N₅O₆S;

¹H NMR (DMSO-d6): 8.52 (br s, 1H), 8.29 (br s, 1H), 4.50 (dd, 1H), 4.04(dd, 1H), 3.47-3.30 (m, 1H), 3.05-3.034 (m, 3H), 2.94-2.86 (m, 3H),2.22-2.19 (m, 2H), 2.03-1.81 (m, 6H).

Example-27 Sodium salt oftrans-6-(sulphooxy)-2-(5-carboxamido-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

By following the procedure described in Example-21 and using carbamoylchloride in the place of acetic anhydride in Step-4, the title compoundwas obtained in 102 mg quantity.

Analysis

MS: 332 (M−H); MF C₉H₁₁N₅O₇SNa; MW 333.28

¹H NMR (DMSO-d6): 8.766 (s, 1H), 8.359 (s, 1H), 4.59 (d, 1H), 4.03 (s,1H), 2.91 (m, 2H), 2.0-2.48 (m, 3H), 1.85 (m, 1H).

Example-28 Sodium salt oftrans-6-(sulphooxy)-2-(5-(R)-piperidin-3-yl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane

By following the procedure described in example-13 and using(R)—N-tert-butoxycarbonyl piperidine-3-carboxylic acid hydrazide in theplace of tert-butoxycarbonylamino acetic acid hydrazide, the titlecompound was obtained in 35 mg quantity.

Analysis:

MS: 372.1 (M−H); MF C₁₃H₁₉N₅O₆S; MW 373.38

¹H NMR (DMSO-d6): 8.70 (s, 1H), 8.54 (s, 1H), 4.59 (dd, 1H), 4.06 (br s,1H), 3.58 (br dd, 1H), 3.15-3.24 (m, 4H), 2.91-3.05 (m, 1H), 2.0-2.14(m, 4H), 1.70-1.90 (m, 5H).

Compounds of the invention described in Example 1 to 28 were preparedusing (5)-pyrroglutamic acid as a starting compound. The absolutestereochemistry is therefore (2S,5R)7-oxo-1,6-diaza-bicyclo[3.2.1]octane ring. Thus, the compound ofExample-4, Sodium salt oftrans-6-(sulphooxy)-2-(5-carboxamido-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octanehas the absolute stereochemistry as Sodium salt of(2S,5R)-6-(sulphooxy)-2-(5-carboxamido-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane.Alternatively, if the starting compound used is (R)-pyrroglutamic_acidthe resulting compounds will have (2R,5S) stereochemistry in7-oxo-1,6-diaza-bicyclo[3.2.1]octane ring. A reference to a compoundaccording to the invention also includes corresponding compounds having(2S,5R) (and 2R,5S) stereochemistry.

Biological Activity

The biological activity of representative compounds according to theinvention against various bacterial strains was investigated. In atypical study, overnight grown bacterial cultures were dilutedappropriately and inoculated on the agar media containing doublingdilutions of the test compounds. Observation for growth or no growth wasperformed after 16-20 hours of incubation at 35±2° C. in ambient air.The overall procedure was performed as per Clinical and LaboratoryStandards Institute (CLSI) recommendations (Clinical and LaboratoryStandards Institute (CLSI), Performance Standards for AntimicrobialSusceptibility Testing, 20th Informational Supplement, M 100-S20, Volume30, No. 1, 2010). The results of these studies are summarized in Tables3 and 4. In general, the stand alone activity of compounds of inventionwas found to be >32 mcg/ml.

The antibacterial activity of representative compounds according to theinvention was also investigated in combination with at least oneantibacterial agent using the above study protocol and the results aregiven Table 3 and 4. As can be seen, the use of compounds according tothe invention significantly lowered MIC values of the antibacterialagent (e.g. in this case Ceftazidime). The results also suggest thecompounds according the invention increase antibacterial effectivenessof the antibacterial agent when said antibacterial agent isco-administered with a pharmaceutically effective amount of a compoundof Formula (I) or a stereoisomer or a pharmaceutically acceptable saltthereof.

TABLE 3 Comparative activity of Ceftazidime (expressed as MIC in mcg/ml)in presence of representative compounds of the invention (eachrepresentative compound is present in a concentration of 4 mcg/ml)Compound of E. coli E. coli E. coli Example No. NCTC 13351 M50 7MP 1 0.51 4 2 16 16 32 3 16 16 32 4 0.5 1 2 5 4 4 16 6 32 16 32 7 16 16 32 8 1616 32 9 2 8 >32 10 16 16 32 11 1 2 32 12 2 8 16 13 0.5 2 8 14 0.5 1 4 150.5 1 8 16 1 2 4 17 1 1 4 18 1 1 4 19 1 4 16 20 0.5 2 8 21 1 2 8 22 4 416 23 1 2 8 24 8 8 16 25 8 8 16 26 1 1 8 27 0.5 2 8 28 >32 >32 >32

TABLE 4 Comparative activity of Ceftazidime (expressed as MIC in mcg/ml)in presence of representative compounds of the invention (eachrepresentative compound is present in a concentration of 4 mcg/ml) ESBLClavulanic Compound according to Example No. Type Strains acid 20 21 231 15 13 14 16 4 17 26 Class A E. coli 0.25  0.25  0.25  0.5  0.25  0.25 0.25  0.25  0.25  0.25  0.25 0.25 ESBL W 13353 E. coli 0.5  0.5  1  1 0.5  0.5  0.5  0.5  1  0.5  1  1 W 13351 E. coli 0.5  4  2  2  2  2  4 2  4  1  2  4 W 13352 Class C E. coli >32  2  2  2  1  1  2  1  2  1  1 1 ESBL M 50 E. coli >32  8  8  8  4  8  8  4  4  2  4  8 7MP E.coli >32  4  2  4  2  2  2  2  2  1  2  2 B 89 KPC K. pneumoniae >32  16 8  8  8  2  8  4  4  1  2  4 ESBL H 520 K. pneumoniae >32  16  8  8  8 2  8  4  4  1  2  4 H 521 K. pneumoniae >32  16  4  8  4  1  4  1  1  1 1  1 H 522 Class D A.baumannii >32 >32 >32 >32 >32 >32 >32 >32 >32 >32 >32 >32 ESBL 13301 A.baumannii >32 >32 >32 >32 >32  16 >32  32 >32  8  16  16 13304

1. A compound of Formula (I)

or a stereoisomer or a pharmaceutically acceptable salt thereof;wherein: Q is heteroaryl; R₁ is: hydrogen, (CO)_(n)—R₃, or COOR₄, n is0, 1 or 2; R₂ is: (a) SO₃M, (b) SO₂NH₂, (c) PO₃M, (d) CH₂COOM, (e)CF₂COOM, (f) CHFCOOM, or (g) CF₃; M is hydrogen or a cation; R₃ is: (a)hydrogen, (b) C₁-C₆ alkyl optionally substituted with one or moresubstituents independently selected from halogen, OR₅, CN, COOR_(S),CONR₆R₇, NR₆R₇, NR₅COR₈, NR₅CONR₆R₇, heterocyclyl, heteroaryl,cycloalkyl or aryl, (c) CN, (d) NR₆R₇, (e) CONR₆R₇, (f) NHCONR₆R₇, (g)aryl optionally substituted with one or more substituents independentlyselected from C₁-C₆ alkyl, OR₅, NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl,SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, or NHCONR₆R₇, (h) heterocyclyloptionally substituted with one or more substituents independentlyselected from C₁-C₆ alkyl, OR₅, NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl,SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, or NHCONR₆R₇, (i) heteroaryl optionallysubstituted with one or more substituents independently selected fromC₁-C₆ alkyl, OR₅, NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl,OSO₂-alkyl, OSO₂-aryl, or NHCONR₆R₇, (j) cycloalkyl optionallysubstituted with one or more substituents independently selected fromC₁-C₆ alkyl, OR₅, NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl,OSO₂-alkyl, OSO₂-aryl, or NHCONR₆R₇, (k) cycloalkyl substituted withC₁-C₆ alkyl wherein C₁-C₆ alkyl is further substituted with one or moresubstituents independently selected from OR₅, NR₆R₇, halogen, CN, orCONR₆R₇, or (l) OR₈; R₄ is: (a) hydrogen, (b) C₁-C₆ alkyl optionallysubstituted with one or more substituents independently selected fromhalogen, OR₅, CN, COOR₅, CONR₆R₇, NR₆R₇, NR₅COR₈, heterocyclyl,heteroaryl, cycloalkyl or aryl, (c) aryl optionally substituted with oneor more substituents independently selected from C₁-C₆ alkyl, OR₅,NR₆R₇, halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, OSO₂-aryl,or NHCONR₆R₇, (d) heterocyclyl optionally substituted with one or moresubstituents independently selected from C₁-C₆ alkyl, OR₅, NR₆R₇,halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, orNHCONR₆R₇, (e) heteroaryl optionally substituted with one or moresubstituents independently selected from C₁-C₆ alkyl, OR₅, NR₆R₇,halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, orNHCONR₆R₇, or (f) cycloalkyl optionally substituted with one or moresubstituents independently selected from C₁-C₆ alkyl, OR₅, NR₆R₇,halogen, CN, CONR₆R₇, SO₂-alkyl, SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, orNHCONR₆R₇; R₅ and R₈ are each independently: (a) hydrogen, or (b) C₁-C₆alkyl optionally substituted with one or more substituents independentlyselected from halogen, CN, CONR₆R₇, NR₆R₇, heterocyclyl, heteroaryl,cycloalkyl or aryl; R₆ and R₇ are each independently: (c) hydrogen, (d)C₁-C₆ alkyl optionally substituted with one or more substituentsindependently selected from halogen, OR₅, CN, COOR₅, CONR₅R₈, NR₅R₈,NR₅COR₈, heterocyclyl, heteroaryl, cycloalkyl or aryl, (e) aryloptionally substituted with one or more substituents independentlyselected from C₁-C₆ alkyl, OR₅, NR₅R₈, halogen, CN, CONR₅R₈, SO₂-alkyl,SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, or NHCONR₅R₈, (f) heterocyclyloptionally substituted with one or more substituents independentlyselected from C₁-C₆ alkyl, OR₅, NR₅R₈, halogen, CN, CONR₅R₈, SO₂-alkyl,SO₂-aryl, OSO₂-alkyl, OSO₂-aryl, or NHCONR₅R₈, (g) heteroaryl optionallysubstituted with one or more substituents independently selected fromC₁-C₆ alkyl, OR₅, NR₅R₈, halogen, CN, CONR₅R₈, SO₂-alkyl, SO₂-aryl,OSO₂-alkyl, OSO₂-aryl, or NHCONR₅R₈, (h) cycloalkyl optionallysubstituted with one or more substituents independently selected fromC₁-C₆ alkyl, OR₅, NR₅R₈, halogen, CN, CONR₅R₈, SO₂-alkyl, SO₂-aryl,OSO₂-alkyl, OSO₂-aryl, or NHCONR₅R₈, or (i) R₆ and R₇ are joinedtogether to form a four to seven member ring.
 2. A compound accordingclaim 1, selected from the group consisting of: trans-sulfuric acidmono-[2-(5-aminomethyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;trans-sulfuric acidmono-[2-(5-((S)-1-amino-ethyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;trans-sulfuric acidmono-[2-(5-((R)-1-amino-ethyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;trans-sulfuric acidmono-[2-(5-(piperidin-4-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;trans-sulfuric acidmono-[2-(5-((S)-pyrrolidin-2-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;trans-sulfuric acidmono-[2-(5-(piperazin-1-yl-methyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;trans-sulfuric acidmono-[2-(5-((RS)-1-amino-1-phenyl-methyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;trans-sulfuric acidmono-[2-(5-(piperidin-4-yl)-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;and trans-sulfuric acidmono-[2-(5-((R)-piperidin-3-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;or a stereoisomer or a pharmaceutically acceptable salt thereof.
 3. Acompound according claim 1, selected from the group consisting of:Sodium salt oftrans-6-(sulphooxy)-2-(5-methyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(5-ethyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(5-trifluoromethyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(5-carboxamido-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(5-(isooxazol-3-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(5-(furan-2-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(5-phenyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(5-(pyridin-2-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(5-(6-carboxamido-pyridin-2-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(5-(5,6-dihydro-8H-imidazo[2,1-c][1,4]-oxazin-2-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(5-(morpholino-4-methyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt of trans-sulfuric acidmono-[2-(5-(morpholin-4-yl-carbonyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester;Sodium salt oftrans-6-(sulphooxy)-2-(5-methyl-[1,3,4]-thiadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(5-methyl-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(5-ethoxycarbonyl-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(2-methyl-2H-[1,2,3,4]-tetrazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(1-methyl-1H-[1,2,3,4]-tetrazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;Sodium salt oftrans-6-(sulphooxy)-2-(3-ethoxycarbonyl-[1,2,4]-oxadiazol-5-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;and Sodium salt oftrans-6-(sulphooxy)-2-(5-carboxamido-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane;or a stereoisomer thereof.
 4. A pharmaceutical composition comprising acompound according to claim
 1. 5. A pharmaceutical compositioncomprising a compound according to claim
 2. 6. A pharmaceuticalcomposition comprising a compound according to claim
 3. 7. A method forpreventing or treating bacterial infection in a subject, said methodcomprising administering to said subject a pharmaceutically effectiveamount of a compound according to claim
 1. 8. A method for preventing ortreating bacterial infection in a subject, said method comprisingadministering to said subject a pharmaceutically effective amount of acompound according to claim
 2. 9. A method for preventing or treatingbacterial infection in a subject, said method comprising administeringto said subject a pharmaceutically effective amount of a compoundaccording to claim
 3. 10. A compound according claim 1, which istrans-sulfuric acidmono-[2-(5-((S)-1-amino-ethyl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester.11. A compound according claim 1, which is trans-sulfuric acidmono-[2-(5-(piperidin-4-yl)-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester.12. A compound according claim 1, which is Sodium salt oftrans-6-(sulphooxy)-2-(5-carboxamido-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane.13. A compound according claim 1, which is Sodium salt oftrans-6-(sulphooxy)-2-(5-methyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane14. A compound according claim 1, which is Sodium salt oftrans-6-(sulphooxy)-2-(5-carboxamido-[1,2,4]-oxadiazol-3-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octane15. A compound according claim 1, which is trans-sulfuric acidmono-[2-(5-aminomethyl-[1,3,4]-oxadiazol-2-yl)-7-oxo-1,6-diazabicyclo[3.2.1]-octan-6-yl]ester.16. A pharmaceutical composition comprising a therapeutically effectiveamount of a compound according to claim
 10. 17. A pharmaceuticalcomposition comprising a pharmaceutically effective amount of a compoundaccording to claim
 11. 18. A pharmaceutical composition comprising apharmaceutically effective amount of a compound according to claim 12.19. A pharmaceutical composition comprising a pharmaceutically effectiveamount of a compound according to claim
 13. 20. A pharmaceuticalcomposition comprising a pharmaceutically effective amount of a compoundaccording to claim
 14. 21. A pharmaceutical composition comprising apharmaceutically effective amount of a compound according to claim 15.22. A method for preventing or treating bacterial infection in asubject, said method comprising administering to said subject apharmaceutically effective amount of a compound according to claim 10.23. A method for preventing or treating bacterial infection in asubject, said method comprising administering to said subject apharmaceutically effective amount of a compound according to claim 11.24. A method for preventing or treating bacterial infection in asubject, said method comprising administering to said subject apharmaceutically effective amount of a compound according to claim 12.25. A method for preventing or treating bacterial infection in asubject, said method comprising administering to said subject apharmaceutically effective amount of a compound according to claim 13.26. A method for preventing or treating bacterial infection in asubject, said method comprising administering to said subject apharmaceutically effective amount of a compound according to claim 14.27. A method for preventing or treating bacterial infection in asubject, said method comprising administering to said subject apharmaceutically effective amount of a compound according to claim 15.